DISCLAIMER ABOUT THIS THREAD:
NO POSTS CONTAINING " Whats the point? " OR ANY VARIATION OF THE SORT. THIS MOD IS FOR THE 'cool' FACTOR. IT HAS NO PERFORMANCE GAIN SO PLEASE DO NOT TREAT IT AS SUCH. THE CAR BELONGS TO THE OWNER AND IF HE WOULD LIKE TO MODIFY IT WITH AN ENGINE START BUTTON, SO BE IT. DO NOT HARASS THE OWNERS ABOUT THEIR DISCISIONS TO MOD THEIR CARS TO ADD THEIR OWN PERSONAL TOUCH.
JiMi_DRiX - I'm not aiming that at you. Just a general statement because it usually happens in mass.
To answer any body who posted and the OP. The way I have it wired is so that you have to putthe key in the ignition and turn it to the on position before you can use the toggle to start the car. It's a pretty neat little gadget to show off to lady friends.

and the turn key start is maintained so in a normal circumstance you can turn and go like usual.
My circuit is super easy! And an S2000 push button could very easily be substituted. I actually am planning on getting one soon. Essentially what the circuit does is takes power from something that gets power when the key is turned to 'ON' like the radio or cig liter, and when the switch or button is engaged sends the power to a point in the ignition circuit downstream from the key. So in my case it goes to the clutch pedal check switch. Which applies power to the start circuit triggering the staterter. I'm sure an auto could do the same thing with the 'Park detector' switch. So it's actually a really easy mod.
Another side not is depending on which wire you put your power to on the clutch check switch you can bypass it all together. Which basically tricks your stang into thinking that the clutch is fully depressed and attempts to roll over the engine. So you can actually leave it in 1st gear and it forces the starter to push the car along. Which is of course not good for the starter. But I'm missing the point here. If you're a lazy ass like me and don't want to depress the clutch every time you start the car, once you check the shifter to see if it's in neutral you flip the swich or push the button and the engine springs to life. It's a very cool and satisfying mod.