Correct me if I am wrong but internal redirects are only available when running under mod_perl in apache. Surely the code you posted will send out a redirect header to the browser if just running as a CGI. This would work but would change the URL displayed.

One way to achieve a solution to the original question would be to have the CGI script request the page off the server and then pass it back to the browser verbatim, as if it were just a proxy.

I may be wrong...

Update: Typo (i before e except after c)