A tip please .!! about htaccess and user restrictions..

Hi apache users.

I got .htaccess working ok on my win32 apache server , but one
functionality
that i cant get to work properly is user restrictions for different
users.

explanation.> if user "mike" logs in trough htaccess/password
protected page
in doc-root he got access to doc-root /htdocs.. ok ..

but if another user "dave" logs in the same way and i only want him to
have access to a specific /dir/ in /htdocs ..for instance >
www/users/guest/dave
how to accomplish this.. ?

greets Lindis