Interesting timing, that this got dug out from the past just as I finished a recent project. The result wasn't as handsome as the one in the first post, but I'm happy with it.
The keyfob I got with my car was pretty beat, specfically the label which had a huge hole in it. I bought a used SVX fob on eBay, which looked okay in the pics but turned out to have the corners worn down to almost nothing; 3 of the 4 brass inserts were exposed and 2 of them spun freely in their holes. But the label was good.
I took both of them apart, including label removal which really isn't hard, and combined the good bits into one decent enough keyfob. I took the remaining mess and, with the help of a bit of patience and some Gorilla Glue, now have a usable-if-gnarly-looking backup fob. New batteries in each, I'm good to go!