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)

70 Roadrunner convt. street car 440+6, NOS, 4-spd, SS springs '96 Mustang GT convt. street car '04 4.6 SOHC, NOS, auto, lowered "Officer, that button is for short on-ramps"