[Zope] GUF

I have GUF installed and I have succeded in coding som managing tools for this. From what i see i have also found a loginpromt (for cookies). My problem lies in that i don't know how to get the user logged in. I try to use userAuthenticate but when i look in the code i see nothing that have anything to do with how to get the user logged in. If i try to use post and sending the login information lika user_pass@zope... I have the problem that thoose user only exist for the "usual" acl_users. Can anybody help me /Mathias