icons = [ ('TopicMap', 'icons/topicmap_icon.gif')
        , ('Topic', 'icons/topic_icon.gif')
        , ('BaseName', 'icons/basename_icon.gif')
        , ('Association', 'icons/association_icon.gif')
        , ('AssociationRole', 'icons/associationrole_icon.gif')
        , ('CMF BTree Folder', 'icons/folder_icon.gif')
        , ('Folder', 'icons/folder_icon.gif')
        ]

def install(self):
    """ This function replaces the icons used for core ZTM Types. """
    pt = getattr(self, 'portal_types')
    for typename, icon in icons:
        ti = getattr(pt, typename, None)
        ti.content_icon = icon
    self.portal_catalog.refreshCatalog()