Originally Posted by xtreme 2
We had a push-button start in Daniel's Datsun 280ZX after the wiring from the key to the ignition burnt out. What we did was installed a Momentary Switch in the dash, ran one side to the battery and the other side to the starter (took off the small wire and put ours in place). You still have to turn the Key to Accessory for this to work, but it keeps you from having to turn the key to crank.
If you want to completely bypass the key, just hook the momentary up how I said, then have an on-off toggle switch that goes from the battery and taps into the Accessory wire. It is the simplest way to do it, and works very well for novice use...