[Zope] Change AUTHENTICATED_USER without standard login screen

Hi, everybody! Is anyone can help me? Problem: I give access to the first page (login page) of my site to everyone (anonymous user). Than, he is entering username and password (the same as Zope's username and password) on this page. Can I change his roles (from anonymous to which one has in Zope) without standard login dialog ? (If can, how?) Many thanks, Alexander Klimovich