I was the one who recommended the clutch-between-shifter-and-handbrake; I actually got this idea from a fellow autocrosser on H-T.
I'm actually trying to see if it will work without having to remove the ashtray; having your car stuck in 3rd or 5th with the handbrake up would make it pretty tough to just steal or drive up a ramp into a truck. I'd imagine this coupled with a typical club on the wheel + autolock would buy you a good deal of time before they cut through everything.
You can buy the autolock at Kragen; they also sell 10 different versions of the club (along with 3-4 different versions of the autolock). I'd imagine pep boys and autozone carry them too.
Shingo