I am trying to achieve this:
http://httpd.apache.org/docs/2.0/ssl...tml#allclients

I have a known set of users that I can provide certificates to for authentication.

However, this configuration option requires a server reboot. I am working on a hosted enviroment, all I have is .htaccess control.

So, I am looking for a similar solution in a PHP Linux MySQL hosted enviroment. Any ideas?