The problem is that the Internal web isn't kept in the web server, it is just a partial drive from the hard disk.
Do you mean by this that the URLs are file:// URIs on a shared drive rather than http:// URIs, and there is no web server involved? If so, You're stuck with client-side scripting. Javascript is about the only option in my mind. VBscript if you want to lock people in to using IE. (And I would reccomend against that. Do you really want to make it harder to change if you ever decide to?)