Funny, I have never had problems figuring things out when it comes to wordpress. I would scoff at the endless posts I read about people not getting this to work when the instructions are so plain and easy to follow.
I couldn't get this thing to serve cached paged either. I messed with it for about an hour, and gave up.
The rewrite rules are in my htaccess, I edited my wp-config file, WordPress is not in a subdomain and everything was enabled. At one point I threw security to the wind, and chmoded to 777, and nothing. WP-cache would cache files fine, supercache cached 2, but everytime it would load a dynamic page, though right below the Dynamic page served in .0075 seconds, it would have a supercache gz line.
I tried this on both Firefox and IE both completely logged out and all cookies deleted, no cache page served.
The only way I could get a cache page served message, was when I disabled the plugin and left the "define" rule in my wp-config file.
I might try later, but I am thoroughly disgusted with myself right now. I know it works, I just cant figure out how.
Version I tried was 0.5.4