A couple of things..
I checked out the one on Ebay that Crazy_Pilot found. If I've interpreted the Chinglish instructions properly, it's not a "touch and release" and the car starts itself. They say to hold the button longer in the winter than in the summer, so I think it'd be safe to assume that it's a momentary switch. Other than that, it gets a lot done for the price.
Absolutely, disabling the steering wheel lock is a safety / theft concern. The only McGuyver for that that I could come up with, that would address the theft issue, would be to energize the brake pedal / shifter lock out function circuit from a protected ( as in only energized by the security system ) circuit. Relays are cheap, you could get creative
Kinda hard to steal something that's stuck in "Park".
My SVX came with a Viper remote. It doesn't start the car, it doesn't have an alarm... no tricks, except for one thing. It immobilizes the ignition. No fob, no start. Lost the fob? First,you need to get into the car, then find the unmarked Viper relay and then push the "secret button". You now have ten whole seconds to stick your key in the ignition and start the car before the immobilizer re-sets. Pretty simple, and I doubt if it was very expensive, but it seems to be quite an effective anti theft method. Any anti -theft system is pretty much a brinkmanship grudge match against the level of determination of the thief. If they want it bad enough, they'll get it. If they can't get it from your house, it'll disappear while you're in the mall. I guess my point being that redundant anti-theft systems would most likely stop anyone but a true pro, or a tow truck and dolly. Personally, I wouldn't disable the steering wheel lock without having at least one other "back up" anti theft device / system.
I'd like to put one in mine too. I know exactly how I want it to function, but I can't find a stand alone fingerprint scanner that will do what I've got in mind.