Well, I have done this a couple of times (for making dynamic URLs thats still fairly easy to remember). If they havn't removed it the last year, its done in the sourceforge code (projects.php).
make a small script called test.php wich contains only something like <?php echo $REQUEST_URI; ?>, then call it by something like:
http://www.host.com/test.php/some/weird/stuff
At least my apache (linux) executes the test.php file, and puts the entire URI into $REQUEST_URI. So, you should be able to get data this way.
Btw, sourceforge has setup their server somehow to execute the projects.php file even if you only call it by 'projects' (without extension). I'm not sure how this is done, but it allows you to go to http://sourceforge.net/projects/mysql , and then the projects.php file reads REQUEST_URI and redirects etc. Pretty cool.