Well I have sketched a very basic diagram that I think will work, but I don't recommend anyone use it without checking it out first. I know this is not done using the correct symbols either, and remember I have
NOT done this on a C5 for real.
You can use the microswitch that's on the C5.
Here's how the circuit works....
Power comes from the battery and enters the relay from the + the relay is open circuit so the motor does not work. When you press the microswitch it powers a small coil in the relay that operates a contact breaker, this completes the circuit to the motor on the positive side and the motor runs. Letting go of the microswitch brakes the power to the coil which in turn opens the contacts in the relay and stops the flow to the motor.
You need to do this because the microswitch will 'weld' its self on with the high current the motor draws.
If the diagram is wrong - someone please tell me and I'll change it.
You can use the red relay from the control box, I think the ones that the C5alive wiring kit uses will also be OK. You might be able to use a standard 70amp relay best if someone else answerer's that.