I use RepetierFirmware. Others have Marlin working. I would say the firmware does not require end stops, but if they are configured it expects them. It requires thermistors to run the heated bed and hot end for safety reasons. Motors should not be required, but don't run a stepper driver without them or you could break your driver. Thermistors could be simulated with resistors if needed, but be sure you keep the temp under control.
You could actually code something simple up that would run the motors without any requirements. The X3 Test code could probably be modified easily enough:
http://files.panucatt.com/X3_test_code.zip That would probably be the easiest way to accomplish your testing via the control board.