Elombard,
Here's a picture of the start button in my BMW racecar project.
To start the engine the ignition key must be in the ON position.
This provides current to the momentary toggle switch.
You press the switch to the right, then push the START button with your thumb.
Wired this way the steering lock will be off, and since you must use two buttons at the same time you will not engage the starter by accident while the engine is running. Still easy one hand operation. You MUST use a relay.
The start button is from a pinball machine! I found it on eBay.
(Got another one that says "To Be Continued". Not sure what to do with that one yet... )
It even comes with a small bulb to light itself.
Good luck!
