Adding custom mod_rewrite rules

I’m writing a plugin, and looking for a way to add custom mod_rewrite rules.

Currently, I’m loading a copy of an archive file. Then there are various $_GET variables. So if my file is ?page_id=12&var1=11&var2=10&var3=9 I want to display /page/var1/var2/var3

Since these vars aren’t in the taxonomy, I’m getting booted to a 404 page.

I’m looking for a way to add my own rules to the rewrite.php file (or whichever file will work best).

Any suggestions?