Clever idea, Chris. I can add something to this from another application - this is how I let folks into our office. Go to Radio Shack and purchase a skylink garage door remote control (don't say no, just yet!). There's a standard momentary button that runs conveniently on 12VDC and powers an internal receiver. Additionally, there's a keyfob (a bit large, but not a dealbreaker) that completes the deal. Best is that these are are sale and cheap ($10?). Model G6M (skyline)

 

This all sounds really cool. I would love to see some kind of write up on this if it ia available...

 

I have actually designed an aftermarket push button start system for older cars that did not offer this as an option, and I also offered a "pit stop mode" which allows the driver to temporarily get out of the vehicle and leave it running, this can be used anywhere from delivery vehicles, emergency vehicles, people who need to run into the store but want to leave the heat or A/C on in there car (maybe for a pet or just to keep the temp right). The problem is security and legal issues about leaving the key in the ignition, with my system you take the key out preventing the the vehicle from being stolen as well as staying legal!and can be installed with or without a remote start system (would be a small difference in price).