DC Gear motor Operation
Using it is as easy as it sounds. You will connect it to power, hopefully through a switch. You need something like nickel metal hydride batteries(forgive my spelling). You need high current at a relatively low voltage, and the first time you do it, do it in pulses of increasing length, checking for heat in each component of the system.

Next, the motor controller should have a pair of pins for power(one from battery, other from ground of battery), pair for the motor, pair for control. control is done by a 50Hz square wave(20ms period) that has a duty cycle between 1.1 and 1.9 mS. The minimum being full reverse, maximum is full forward, 1.5mS will be idle. There are also controllers that use on and off, but you probably have one of the nicer ones.

To control it electrically I suggest a power MOSFET or BJT. MOSFET is probably more what you will want.

PLEASE NOTE: when you use any sort of electrical control(a MOSFET you pick or such) you need to have a diode, reverse biased in normal opperation, pointing from ground pin of the motor to the high side. This needs to be a relatively large diode in operating current. The motor will act as a voltage source and can generate very high voltages, as it is pretty much a large inductor. This diode will allow the current a path that does not involve over-voltage'ing your motor.