[Zope] About LDAPUserFolder, memberships and LocalRoles...

Hi, I use LDAPUserFolder and when I want to assign LocalRoles I get into trouble because users are not display if they never login a first time. I think that when a user make a login it is registered as membership and he can be listed by LocalRoles. So the question is how can I register my LDAP users as membership automaticaly ? Thanks.