[JRMichler]

Definitely kill the injectors, not the ignition. Here's how I did my kill switch:

The kill switch was installed 12-7-2008. It breaks the connection through the fuel injector fuse to kill the engine. I cut the plastic off a spare fuse, removed the fuse element, and soldered wires to the fuse pins. These wires were connected to an automotive relay. The relay coil is energized through a pushbutton switch mounted on the shift lever. The relay is connected normally closed, so the circuit is opened when the relay coil is energized. The fuel injector circuit has an inline fuse, with another inline fuse in the wire to the pushbutton. I can bypass the kill switch any time by pulling the connectors from the fuse box and putting a fuse back in. All wires are protected by fuses. This is especially important when running wires through the firewall, under carpeting, and up the shift lever.

The kill switch works well, however I randomly get a CEL. The CEL is either a P0204 or P0461. I just reset using the Scangauge. Strangely, I always get a CEL at the first EOC after filling the tank. That CEL is also accompanied by the gas gauge moving to Empty. The gas gauge stays at empty until the CEL is reset. The BCM also relocks all the door locks every time at a bump start.