authentication

I have one directory that is protected with an .htaccess file on my server where I store all member content. What I want to do is have a page where members can log in, and after they have entered there user name and password I what the php script to authenticate them against the .htaccess file. If they are authenticated I would like to keep track of that as one of there session variables, so that they do not have to re-authenticate when they try to access content in the protected directory. Essentially what I am trying to do is give them access to the .htaccess protected based from a "submit form". Instead of requiring that they get the standard user name and password pop up window that one gets when you try to access a directory that is password protected on Apache.