I haven't found any other triggers for vehicles except for Space/Jump, which in Kaje's "VehicleData::onTrigger(%this, %obj, %num, %cli)", %num is 2 - %cli is whether you are pressing or releasing it. Crouch plus the left and right clicks are put to the player (weapons, jet to unmount), and vehicle movement is handled by setControlObject, not a trigger from moveForwards(); moveBackwards(); etc.