Moses,
Years ago I used parts from an old JVC video camera to remotely turn a 10 turn potentiometer. I used the zoom control button and circuit board with the zoom motor and gears to turn the pot. The button (zoom in/out) was some sort of variable resistance control and allowed for very slow, fine, smooth, control of the motor direction and speed. It operated from 12 volts. If you can find an old camera like that, you may be able to hack it apart.