using wp-facebookconnect with wp-supercache shows a page full of weird chars

I’m trying to set up this plugin, and I think I have it working, with the exception of Firefox on a Mac. However, when I try to use wp-supercache, following the instructions here (https://www.allfacebook.com/2008/12/how-to-make-facebook-connect-work-with-wp-super-cache/) I added the mod_rewrite rules, but when I create the php file I get a page full of strange characters when the page reloads. Anybody have any ideas on that? Unfortunately, I’m working on a live site so it’s tough to do the trial and error approach.