I REALLY like slantzilla's idea of wiring into the brake light switch.
If you have a 4-speed car, then maybe a push button the shifter? I have a 2-step which isn't installed yet and plan to wire it together with a line lock to a switch on the shifter (since I need both feet to launch & I have 3 pedals)
If you have a clutch the switch goes on the clutch pedal, not on the line lock. I don't care how good you are, you will never get the button off at the correct time twice in a row.
Set it up on the pedal and make sure that as soon as you move your foot the switch clicks. That way, your not loading the engine while the two step is on. That's a promised parts breaker.
