I have a perlscript that was written by WorkMule that will do a fair bit of the work for you, but you'll still have quite a fair amount you'll have to do by hand.
You can use the pearl script, but it will only replace the existing HTML colors and stuff. It wont make custom classes that you will probably need for your sites CSS file.
Actually it comes with a custom CSS file that can easily be modified to suit your site once you've run the conversion, WorkMule did a really nice job on it , think Brad contributed a little too with bundling it up.