I'm going that way too, thanks to Jedi Sol's excellent explanation of his own work. This is what I have lined up for mine:
A normally closed, momentary open pushbutton switch
A relay and socket
Some connectors
A "Fuse Buddy"
Basically, just looking at the add-a-circuit makes me think "I see how I can get power from it, but how do I open and cloer the circuit with just the one wire?" The Fuse Buddy made more sense to me- one wire on one side and one wire on the other. I cut the leads off and I'm just waiting for some time to solder everything together and drill a discretely placed hole to mount the button.
I did test it- I put the Fuse Buddy in the injector fuse slot, held the wires together and started up. After I got rolling I separated the wires, then put them back together, bump started and parked the car. And promptly haven't had any time to put it together properly.