How to track a specific user after basic authentication

I have successfully implemented basic authentication with apache on a site: the user needs to enter username and password on that horrible browser pop-up box, and then he has access to the restriced areas so he can read restricted material.  Works fine.  But now I'm working on a site where, when the user gains access, the CGI programs (perl) need to know *which* user is there, so, for example, he can see *his* account information or *his* customized pages.  I can't figure out how the perl programs identify the specific user upon his entry into the restricted area, and then keep track of which user it is as he navigates pages in the restricted section.

I can figure out some workarounds, like receiving and then passing back user name in a hidden form field on every page that the user sees in the restricted area, but I'm looking for a more straightforward solution that I hope exists.

Question that is possibly answered as part of a solution: is there any way to allow the user to gain access with UserName and Password fields on the page that I create, rather than that little browser popup box?
Thanks.
--Steve D.