You'll have to edit auth.pl and make sure that auth_check_passwd returns the authority type as well. Then in db.cgi change:

($status, $uid, $per_view, $per_add, $per_del, $per_mod, $per_admin)
= &auth_check_password; # Authenticate User, get permissions and userid.

to:

($status, $uid, $per_view, $per_add, $per_del, $per_mod, $per_admin, $per_authtype)
= &auth_check_password; # Authenticate User, get permissions and userid.

Now you can use it in the html.pl.

Hope this helps!

Alex