[Zope] Changing Permissions in ZClasses

Hi, I have a ZClass that creates a Client Tree, with various folders etal in the instance. I have also added an user_acl to make the the subtree private. All works dandy except I can't find how to turn off the anonymous View inherit permission. Ideally I want a dtml-call command to negate the inherit view permission. Any pointers, FAQ references, etc? Thanks in advance