Controlling Traxxis XL5 Motor Controller

Hi, I'm working on automating an RC to compete in a competition in several months, and I'm having no luck controlling the motor (which is quite important). I can control the steering by just using the Servo object, and I was told that the motor controller is run the same way. As I do not have an oscilloscope, I was wondering if anyone could help me figure out how the motor controller works. As I'm not exactly rolling in cash, I'd rather not replace a good motor controller because I can't figure out what input it requires.