Sorry I haven't gotten around to this, I've been doing some upgrading and having some internet troubles. Anyway, folding for radeons got a big boost with the v7 beta client, you should try using that first off: https://fah-web.stanford.edu/projects/FAHClient/wiki/BetaRelease
Besides that, there are some lots of unique settings you need to set up for radeons, I've never used one so I'm not personally familiar, but there's help out there. The best place to look would be the ati forum in foldingforum.org, here's a link http://foldingforum.org/viewforum.php?f=51
It's usually harder than nvidia cards, so it'll be a little more work, but it should be possible.