The issue with just using the control panel is that it brings up a lot of errors due to issues such as the incline motor not being attached. I suspect that I may have to follow Nickp's advice and build up from the motor, discarding the board.
My understanding was that there was a small voltage sent from the control panel to the motor control bit that altered the PWM with the change in voltage. Therefore a potentiometer could easily control this voltage. Although it seems the model I have may not be so simple.