The universal dock won't really work with the sl2 without modifying it. I Dremelled one when the sl100 first came out, because there weren't any other docks available, so It will function, but it won't fit.
Taylor is right. I wasn't trying to encourage you to do this, because it's not a very good solution. I was just saying that it was possible. If you already have the power cord and antenna, you can buy just a bare dock.