Unfortunately I have no experience with the Cherokee web server. However, looking at the documentation, I would recommend to follow the approach in their
Wordpress recipe. That's what I usually do when confronted with a new web server.
Their regex solution for index.php is a common one and should work for BBS, too. The directories with static content are "/style" "/img" and "/js" so you would have to create a Directory rule for each of them. The only other static file is "/installcheck.php". That is all.
If you get it working, could you please add some infos to the wiki?
HTH,
Rainer