Unfortunately this is not currently possible :(. I just checked in design/admin2/templates/contentstructuremenu/content_structure_menu_dynamic.tpl and it actually just excludes some content classes. Besides, it seems that (undocumented) fetch function - class/list_by_groups - used in that template to list possible classes does not check security policies (eZClassFunctionCollection::fetchClassListByGroups()).
This would be really nice to get that feature IMHO :). Would you mind add a new enhancement issue on issues.ez.no ?
