What I think you may be looking for(*) is PATH_INFO, which is a value that your webserver will pass to a script when that script is the last thing the server can find ON the path, but not at the end of the path.

An example might make this clearer: Suppose I have a script called test.pl in my cgi-bin directory. Now suppose the server gets a request for

/cgi-bin/test.pl/some/extra/stuff

There is no file at the end of that path, so it backs up until it finds something that *does* exist, namely test.pl, and passes all the "extra" stuff to that as PATH_INFO, i.e. $ENV{PATH_INFO} is set to

/some/extra/stuff

Does that help?

* OK, I'm sure merlyn's written an article about this that will tell you more than I just have, and I'm reasonably confident he'll give you the URL once he sees your node =) But this should get you started.