I would say probably not because .htaccess passwords are encrypted and the list of allowable usernames is stored in a file. That would mean that every time a user registered you would have to grab their password, encrypt it into .htaccess, and add the username to the list. Also, I don't believe its possible to bypass the login screen since the first file read in a directory with .htaccess is .htaccess itself, which means that you could not have a file to check if they were already logged in until they were already past the .htaccess login screen. I hope that makes sense and helps a little.