you can get a 3-position switch at just about any store that sells automotive accessories (auto-zone for sure has them). it would be as simple as grounding the switch, running one power wire from the switch to the carnetix, and then run the IGN and BAT to the different nodes on the switch. should be as simple as that. Obviously, check the instructions on the particular switch before starting, as well as hold off actually hooking the power wire into the carnetix until you run some tests with a voltmeter or ground light to make sure your wiring is correct. Overall it should be very simple.