Yep, that switch is hard to find at RS. They used to carry it on the card wall, but no more.
You're talking about the 'pin switch' that is a screw in cylinder that when the pin is pressed, it doesn't ground out. When the door opens, the switch grounds.
I have a remote start on one of my cars, and that was use as the hood interlock switch. I went EVERYWHERE local looking for one when it broke. For a while I left it disconnected so my remote start would work.
Anyway, one day I swung into one of those 'car stereo' stores along the highway that also had a sign up that they install remote starters and they had a whole drawer of the things. Reasonably priced too.
I did find them online at one the remote starter web sites, but they were just plain on drugs for what they wanted for the things, and they had a huge minimum order.
Mike