My $0.02...
Your question is "How to wire it"
My car came with a hot start relay (Pelican Kit). Why a hot start relay? The wiring takes a heavy and high wattage load to crank the car. The relay kit sends the juice directly to the relay and starter while the stock wiring is used to simply "click" the hot start relay into position. This will help to preserve your wiring AND you can use a switch that is not super heavy duty since only the relay will be "clicked."
My car also came with a start button. The ignition must be turned on, but the start button prevents wear on the contacts that are in the bottom of the key (inside the steering column).
My switch is wired into the steering column support bracket (a 1/2" hole) and it is out of sight. There are two heavy duty copper stranded wires that run from the push button switch under the side sill plate, through the sound padding, into the engine compartment, under the relay board, over hill, over dale, etc... and down to the starter. One wire on each post. This jumper method is almost identical to how a mechanic would use a hand-held hot start button while working on an engine.
ALSO:
Push Buttons from JC Whitney:
http://www.jcwhitney.com/item.jhtml?ITEMID=40288
I HATE their freight costs!
Waterproof Jeep Switch:
http://store.yahoo.com/webjeeps/jeepwatpusst.html
E-Switch
http://www.e-switch.com/types/push.html
Good luck with your project.
Joe
[This message has been edited by retro74 (edited 09-11-2001).]