I'm not 100% sure, but I'm guessing the switch is a normally open, so when you press the clutch in it closes the circuit. Unplugging the harness from the switch and installing a jumper should bypass the switch.
They started putting these things in so that you couldn't start the car w/o the clutch disengaged and it's something I never really believed in, especially if the car dies on a RR track w/ a train coming (I know, million in one chance) but you'd have to bail and leave the car, where as w/ a car w/o the switch, you can put it in gear and use the starter to get off the track...