Use Redirection plugin to $redirect_url = "http://mydomain.com/$subdomain"

I need to redirect any subdomain so that it points to a folder that really doesn’t exist to create a custom page for my people. Their subdomain can change at their whim and many are added everyday so it cannot be static. Is there a better way to do this using the redirect plugin? or anything else?
$redirect_url = “http://mydomain.com/$subdomain”;
echo “<meta http-equiv=’refresh’ content=’0;url=$redirect_url’>”;

http://wordpress.org/extend/plugins/redirection/