A better way to handle multiple client authentication?

Right now I have an application set up for multiple clients: clientA, 
clientB, clientC.

Each client has their own users.

The way I have it setup is clientA goes to http://www.site.com/clientA 
and is presented with a login screen which is triggered by an .htaccess 
file in a directory called /clientA. The .htaccess file directs Apache 
to perform DBI-based authentication using Apache::AuthDBI.

PerlSetVar Auth_DBI_data_source DBI:mysql:clientA

This works great, but I am aware of the limitations and I would like to 
set up some rules in the Apache config that accomplish this all without 
.htaccess files in every directory for every client (gonna get tricky 
around 100,000 clients for sure!)

Is this even possible? Can I do something like:

RewriteRule ^/(.+)/$ PerlSetVar Auth_DBI_data_source DBI:mysql:$1

Or do I have to create my own authentication module?

Thanks for any direction... And sorry if this is better for the Apache 
mailing list, I'm always a bit uncertain which group I should ask first...

Tosh

-- 
McIntosh Cooey - Twelve Hundred Group LLC - http://www.1200group.com/