I am writting the below code in httpd-vhosts.conf. but it is not working for me… Can anyone explain me where I am wrong.

RewriteCond %{LA-U:REMOTE_USER} (.+)
RewriteRule ^%{HTTP_HOST}:8080/seaside/UserLoginPage?userid=%1$ %{HTTP_HOST}:8080/seaside/UserLoginPage?[L]

I want to remove query string from my URL but I need it also while I logged in my home page. If any one know any other way of doing this so that I can retain my authantication.
I really stuck with this problem and need to solve it urgently...

Thanks & Regards