Hi jediknight36;
I can't help with the wind up key, but I have put in an air horn without removing any panels, and for about $10.
I have a tutorial on the installation on my web site,
www.bluemaxmods.com.
I kept my regular horn and added the airhorn on a separate circuit. I hooked my wiring directly to the battery (fused), but you could also tap into the car's fuse block.
I think the eviloution site also has information you could use.
Good luck
Pete