To retrieve 360 degree readings for your physics engine angles - if(my.pan < 0){my.pan += 360;}

To find the positive force on your wheels -
phent_getvelocity(my, temp, vector(250,250,0));
temp = abs(temp);

To find magnitude of velocity -
phent_getvelocity(my, temp, nullvector);
temp = vec_length(temp);

To find angular velocity -
phent_getangvelocity(you, temp);

You probably already know these commands well enough, but just in-case. If you end up working this out, please share how you accomplished it; I'd be very interested to know what you've done. Thanks.