[Cuog]

Do you mean you want to make a normal motor act like a servo? if so then u will also need a potentiometer and what u do is hook the pot up to whatever it is that must rotate and compare the value of that pot to where u want the motor facing then drive the motor until it reaches that point, i would recomend that u do this after the motor has bee geared down and u are comparing the overall displacement of the motor as this will be easier to implement.