Camera Tracking Using Motors Instead Of Servos?

I have finally reached the point of integrating my EZ-B into my robot. Right out of the gate I have run into a question. Can anyone tell me if a script can be written to have the camera track, using motors with potentiometers, instead of servos? My robot is too big for servos (well, actually my budget is too small for the servos that I would need), but I would like to incorporate the motion and facial tracking to turn the head, and bend him at the waist. If someone could point me in the right direction, I would be grateful.