[Zope] Expanding the User Object

hi y'all! in a product we need to store a lot of data for a user, while still having to apply zope's access control features to it. it seems like we can not add our own objects (which are derived from accesscontrol.user.user) to the acl_users folder. are we doing something wrong or is there a work around or do we really have to store two different objects to achieve this goal? ciao, alex