I had this same problem in the middle of a ride. Luckly, I used my buddies key to short the switch to start the bike.
The replacement switch has a plastic connector that feeds down the center of the frame. Just follow the wires.
For some reason, I remember being in the wire bundle on the left side - had to remove the plastic to get to the bundle.
I did not cut the plastic around the wiring, but it was a pain to unplug the connector.