[otrs] Passing Authorized User to index.pl

We have a company intranet protected by htaccess/htpasswd. After logging in, support (OTRS) is available as a link to load in a right frame. I have appended the REMOTE_USER variable to the index.pl link and would now like to have the username show up in the username box for login when the link is clicked. So given: http://www.mysite.com/otrs/index.pl?User=somebody how do I get somebody into the User input box? I've tried a few various hacks but can't seem to determine exactly where the query string elements end up. I should mention the intranet and OTRS are on different servers so the username has to be passed as a link. Charles