There is no official command-line option for that, but with Pianoteq 6.1 you can use:
--list-param to get a list of public parameters (similar to the list VST parameters).
--set-param name=value to change the value of a parameter . If the parameter name contains spaces you must quote it , for example:

./Pianoteq 6  --set-param "Reverb Duration=5"
Options from command-line:
 --help             : show this help, and quit
 --version          : show current version number and date, and quit
 --no-prefs         : start Pianoteq without using any saved preference
 --no-audio-prefs   : start Pianoteq with a clean audio/midi configuration
 --prefs FILENAME   : stores the preferences in the specified file
 --fxp FILENAME     : load an FXP file on startup
 --preset NAME      : load a preset on startup
 --list-presets     : display the list of all presets
 --midimapping NAME : load a midimapping preset on startup
 --midi-channel CH  : listen only to MIDI events on the specified channel (1<=value<=16 or 'all')
 --midi-transpose x : transpose note events by the specified amount (-36<=x<=36)
 --midi FILENAME    : load a midi file, or a *.m3u playlist content. If filename is a folder,
                      the midi files contained in that folder
 --open file1 file2 ...     : load files, which can be midi, fxp, mfxp, ptq, scl or kbm files.
                      Must be used as the *last* option
 --wav FILENAME     : export midi file as WAV file, and quit
 --flac FILENAME    : export as FLAC
 --mp3 FILENAME     : export as MP3
 --rate FREQ        : change the sample rate for the exported wav
 --bit-depth D      : change the bit-depth for the exported wav (16,24 or 32)
 --dither ON/OFF    : turn dithering when exporting on or off
 --normalize        : turn on volume normalization for the exported wav
 --normalize-db DB  : change the normalization level (default value is -1dB)
 --mono             : export the wav file as mono
 --headless         : do not show the graphical interface
 --fullscreen       : start in fullscreen mode
 --export-vst3-presets PATH : export all presets as VST3 presets
 --export-vst3-presets-std  : export VST3 preset to their default location, which is:
                    C:\Users\davea\AppData\Roaming\VST3 Presets\
 --export-presets-filter all|builtin|ptq|user : select which presets are exported, default is 'builtin'
 --restore-windows  : restore the a previously saved set of windows
 --do-not-block-screensaver : prevent Pianoteq from keeping the screen on
 --quiet            : be less verbose
 --play             : immediately start playing the midi file
 --play-and-quit    : start playing the midi file, and quit when it ends
 --activate SERIAL or --activate COMPUTER_NAME:SERIAL activate this computer using the supplied serial
 --serve [IP:]PORT  : start a JSON-RPC server for remote control of Pianoteq.
                      When using --serve "" , the server listens on localhost:8081

Example of use: Pianoteq --preset "U4 Small" --midi foo.mid --wav foo.wav
"Pianoteq 7.exe" --list-param

c:\Program Files\Modartt\Pianoteq 7>   1;                                Condition;          0..10.00
   2;                                 Dynamics;          1..100
   3;                               Pitch Bend;      -2400..+2400
   4;                             Unison Width;          0..20.00
   5;                             Stereo Width;          0..5.00
   6;                             Hammer Noise;       0.10..3.00
   7;                            Sustain Pedal;          0..1.00
   8;                               Soft Pedal;          0..1.00
   9;                          Sostenuto Pedal;          0..1.00
  10;                           Harmonic Pedal;          0..1.00
  11;                             Rattle Pedal;          0..1.00
  12;                          Buff Stop Pedal;          0..1.00
  13;                            Celeste Pedal;          0..1.00
  14;                              Mozart Rail;          0..1.00
  15;                          Super Sostenuto;          0..1.00
  16;                     Pinch Harmonic Pedal;          0..1.00
  17;                          Glissando Pedal;          0..1.00
  18;                   Harpsichord Register 1;          0..1
  19;                   Harpsichord Register 2;          0..1
  20;                   Harpsichord Register 3;          0..1
  21;                         Reversed Sustain;          0..1
  22;                                   Volume;        Off..+12.0
  23;                         Post Effect Gain;      -12.0..+12.0
  24;                                 Diapason;      220.0..880.0
  25;                        Octave Stretching;       0.95..3.00
  26;                           Unison Balance;      -1.00..+1.00
  27;                    Direct Sound Duration;          0..5.00
  28;                       Hammer Hard. Piano;          0..2.00
  29;                       Hammer Hard. Mezzo;          0..2.00
  30;                       Hammer Hard. Forte;          0..2.00
  31;                       Spectrum Profile 1;     -15.00..+15.00
  32;                       Spectrum Profile 2;     -15.00..+15.00
  33;                       Spectrum Profile 3;     -15.00..+15.00
  34;                       Spectrum Profile 4;     -15.00..+15.00
  35;                       Spectrum Profile 5;     -15.00..+15.00
  36;                       Spectrum Profile 6;     -15.00..+15.00
  37;                       Spectrum Profile 7;     -15.00..+15.00
  38;                       Spectrum Profile 8;     -15.00..+15.00
  39;                             Strike Point;     1/64.0..1/2.0
  40;                     Pinch Harmonic Point;     1/64.0..1/2.0
  41;                          Pickup Symmetry;          0..1.00
  42;                          Pickup Distance;       0.20..2.00
  43;                               Soft Level;          0..1.00
  44;                         Clavinet Low Mic;      -1.00..+1.00
  45;                        Clavinet High Mic;      -1.00..+1.00
  46;                                Impedance;       0.30..3.00
  47;                                   Cutoff;       0.30..3.00
  48;                                 Q Factor;       0.20..5.00
  49;                            String Length;       0.80..10.00
  50;                    Sympathetic Resonance;          0..5.00
  51;                   Duplex Scale Resonance;          0..20.00
  52;                         Quadratic Effect;          0..20.00
  53;                        Hammer Tine Noise;    -100.00..+25.00
  54;                          Blooming Energy;          0..2.00
  55;                         Blooming Inertia;       0.10..3.00
  56;                         Equalizer Switch;        Off..On
  57;                               Aftertouch;          0..1.00
  58;                                 Morphing;          0..100
  59;                            Bounce Switch;        Off..On
  60;                             Bounce Delay;      10.00..250.00
  61;                              Bounce Sync;        Off..On
  62;                        Bounce Sync Speed;        16d..1/8t
  63;              Bounce Velocity Sensitivity;          0..100
  64;                        Bounce Delay Loss;          0..100
  65;                     Bounce Velocity Loss;          0..100
  66;                      Bounce Humanization;          0..100
  67;                             Eff 1 Switch;        Off..On
  68;                             Eff 1 DelMix;          0..100
  69;                            Eff 1 DelTime;          1..1000
  70;                              Eff 1 DelFb;          0..100
  71;                            Eff 1 DelTone;      -1.00..+1.00
  72;                             Eff 1 DelPol;        Off..On
  73;                            Eff 1 Param 6;          0..1.00
  74;                            Eff 1 Param 7;          0..1.00
  75;                            Eff 1 Param 8;          0..1.00
  76;                             Eff 2 Switch;        Off..On
  77;                              Eff 2 PEQ1F;         40..22050
  78;                              Eff 2 PEQ1G;      -25.0..+25.0
  79;                              Eff 2 PEQ1Q;       0.01..100.00
  80;                              Eff 2 PEQ2F;         40..22050
  81;                              Eff 2 PEQ2G;      -25.0..+25.0
  82;                              Eff 2 PEQ2Q;       0.01..100.00
  83;                              Eff 2 PEQ3F;         40..22050
  84;                              Eff 2 PEQ3G;      -25.0..+25.0
  85;                             Eff 3 Switch;        Off..On
  86;                              Eff 3 PEQ1F;         40..22050
  87;                              Eff 3 PEQ1G;      -25.0..+25.0
  88;                              Eff 3 PEQ1Q;       0.01..100.00
  89;                              Eff 3 PEQ2F;         40..22050
  90;                              Eff 3 PEQ2G;      -25.0..+25.0
  91;                              Eff 3 PEQ2Q;       0.01..100.00
  92;                              Eff 3 PEQ3F;         40..22050
  93;                              Eff 3 PEQ3G;      -25.0..+25.0
  94;                            Reverb Switch;        Off..On
  95;                          Reverb Duration;          0..5.00
  96;                               Reverb Mix;        Off..+50.0
  97;                          Room Dimensions;       5.00..50.00
  98;                         Reverb Pre-delay;          0..0.200
  99;                 Reverb Early Reflections;      -20.0..+20.0
 100;                              Reverb Tone;      -1.00..+1.00
 101;                          Reverb Envelope;     -200.0..0
 102;                        Reverb Resampling;         50..200
 103;                           Limiter Switch;        Off..On
 104;                        Limiter Sharpness;          0..2.00
 105;                        Limiter Threshold;        -25..0
 106;                             Limiter Gain;        -30..+6
 107;                                     Mute;          0..1.00
 108;                             Damper Noise;        Off..+24.00
 109;                          Damper Position;     1/64.0..1/2.0
 110;                              Last Damper;          0..128
 111;                              Pedal Noise;        Off..+25
 112;                        Key Release Noise;        Off..+25
 113;                         Damping Duration;       0.03..10.00
 114;                    Keyboard Range Switch;        Off..On
 115;                             Lid Position;          0..1.00
 116;                              Output Mode; Sterophonic..Binaural
 117;                   Mic Level Compensation;        Off..On
 118;                   Mic Delay Compensation;        Off..On
 119;                          Head X position;    -10.000..+10.000
 120;                          Head Y position;     -6.000..+6.000
 121;                          Head Z position;          0..3.500
 122;                            Head Diameter;     10.000..50.000
 123;                               Head Angle;     -180.0..+180.0
 124;                         Mic 1 Mic Switch;        Off..On
 125;                         Mic 1 X position;    -10.000..+10.000
 126;                         Mic 1 Y position;     -6.000..+6.000
 127;                         Mic 1 Z position;          0..3.500
 128;                            Mic 1 Azimuth;     -180.0..+180.0
 129;                          Mic 1 Elevation;     -180.0..+180.0
 130;                            Mic 1 Level 1;        Off..+6
 131;                            Mic 1 Delay 1;     -250.0..+250.0
 132;                            Mic 1 Level 2;        Off..+6
 133;                            Mic 1 Delay 2;     -250.0..+250.0
 134;                            Mic 1 Level 3;        Off..+6
 135;                            Mic 1 Delay 3;     -250.0..+250.0
 136;                            Mic 1 Level 4;        Off..+6
 137;                            Mic 1 Delay 4;     -250.0..+250.0
 138;                            Mic 1 Level 5;        Off..+6
 139;                            Mic 1 Delay 5;     -250.0..+250.0
 140;                         Mic 2 Mic Switch;        Off..On
 141;                         Mic 2 X position;    -10.000..+10.000
 142;                         Mic 2 Y position;     -6.000..+6.000
 143;                         Mic 2 Z position;          0..3.500
 144;                            Mic 2 Azimuth;     -180.0..+180.0
 145;                          Mic 2 Elevation;     -180.0..+180.0
 146;                            Mic 2 Level 1;        Off..+6
 147;                            Mic 2 Delay 1;     -250.0..+250.0
 148;                            Mic 2 Level 2;        Off..+6
 149;                            Mic 2 Delay 2;     -250.0..+250.0
 150;                            Mic 2 Level 3;        Off..+6
 151;                            Mic 2 Delay 3;     -250.0..+250.0
 152;                            Mic 2 Level 4;        Off..+6
 153;                            Mic 2 Delay 4;     -250.0..+250.0
 154;                            Mic 2 Level 5;        Off..+6
 155;                            Mic 2 Delay 5;     -250.0..+250.0
 156;                         Mic 3 Mic Switch;        Off..On
 157;                         Mic 3 X position;    -10.000..+10.000
 158;                         Mic 3 Y position;     -6.000..+6.000
 159;                         Mic 3 Z position;          0..3.500
 160;                            Mic 3 Azimuth;     -180.0..+180.0
 161;                          Mic 3 Elevation;     -180.0..+180.0
 162;                            Mic 3 Level 1;        Off..+6
 163;                            Mic 3 Delay 1;     -250.0..+250.0
 164;                            Mic 3 Level 2;        Off..+6
 165;                            Mic 3 Delay 2;     -250.0..+250.0
 166;                            Mic 3 Level 3;        Off..+6
 167;                            Mic 3 Delay 3;     -250.0..+250.0
 168;                            Mic 3 Level 4;        Off..+6
 169;                            Mic 3 Delay 4;     -250.0..+250.0
 170;                            Mic 3 Level 5;        Off..+6
 171;                            Mic 3 Delay 5;     -250.0..+250.0
 172;                         Mic 4 Mic Switch;        Off..On
 173;                         Mic 4 X position;    -10.000..+10.000
 174;                         Mic 4 Y position;     -6.000..+6.000
 175;                         Mic 4 Z position;          0..3.500
 176;                            Mic 4 Azimuth;     -180.0..+180.0
 177;                          Mic 4 Elevation;     -180.0..+180.0
 178;                            Mic 4 Level 1;        Off..+6
 179;                            Mic 4 Delay 1;     -250.0..+250.0
 180;                            Mic 4 Level 2;        Off..+6
 181;                            Mic 4 Delay 2;     -250.0..+250.0
 182;                            Mic 4 Level 3;        Off..+6
 183;                            Mic 4 Delay 3;     -250.0..+250.0
 184;                            Mic 4 Level 4;        Off..+6
 185;                            Mic 4 Delay 4;     -250.0..+250.0
 186;                            Mic 4 Level 5;        Off..+6
 187;                            Mic 4 Delay 5;     -250.0..+250.0
 188;                         Mic 5 Mic Switch;        Off..On
 189;                         Mic 5 X position;    -10.000..+10.000
 190;                         Mic 5 Y position;     -6.000..+6.000
 191;                         Mic 5 Z position;          0..3.500
 192;                            Mic 5 Azimuth;     -180.0..+180.0
 193;                          Mic 5 Elevation;     -180.0..+180.0
 194;                            Mic 5 Level 1;        Off..+6
 195;                            Mic 5 Delay 1;     -250.0..+250.0
 196;                            Mic 5 Level 2;        Off..+6
 197;                            Mic 5 Delay 2;     -250.0..+250.0
 198;                            Mic 5 Level 3;        Off..+6
 199;                            Mic 5 Delay 3;     -250.0..+250.0
 200;                            Mic 5 Level 4;        Off..+6
 201;                            Mic 5 Delay 4;     -250.0..+250.0
 202;                            Mic 5 Level 5;        Off..+6
 203;                            Mic 5 Delay 5;     -250.0..+250.0
 204;                              Sound Speed;        200..500
 205;                            Wall distance;          0..6.00
 206;                                      Lid;        Off..On
