ModRewrite code required for permalinks

Similar to Wordpress permalinks I need a structure translated so that it can be viewed as a subdomain. This is not for SEO purposes but merely to look good to human readers. The site contains a number of portals that contain paths like this:- [login to view URL] [login to view URL] [login to view URL] [login to view URL] An entry in the htaccess needs to be made for each so that they could be accessed as follows [login to view URL] [login to view URL] [login to view URL] [login to view URL] This should be for any file found in the directory, not just [login to view URL], so... [login to view URL] would refer to... [login to view URL] Each server will hold up to 1000 or more subdmains. If this will have a noticeable impact on performance then your advice and suggestions on how this can be reduced would be welcome. The development is on a dedicated Linux server running cpanel and Centos 64bit Linux running Apache 2.2 and I have root access if module changes are needed.