I have seen a lot of people use a Honda S2000 push button start. You can move the 12v outlet down to the passenger foot well and use the empty hole to mount the switch.

YouTube video of a start button where 12v outlet was.

http://www.youtube.com/watch?v=D-K9z3XnOKk

Here is a link to an install in a Miata and a link to the switch $38.30.

http://www.revlimiter.net/mods/s2000_button.html

The switch is at the bottom of the page.

http://www.handa-accessories.com/s2000-03.html