[Zope] From database to acl_users

Hi, I know how to get users/passwords/roles in straight Python/mxOdbc from a corporate database. I want to give Zope permissons to those users in addition to those from the "acl_users" folder. Means that when a user logs for basic authentication, it's credentials must be compared with "natural" acl_user folder then with this database. Any idea or related product ? TIA. --Gilles