someone had code pertaining to phpbb permissions on the pages of wowroster.
I have the link from the old forums still
but I bet that wont help.
What it would do is not let anyone see a page as they must be logged inm, making the pages themselfs based on phpbb2 permissions.
IE, if you wanted the admin page double secure, add the code to the top of the page. Then the user who is int he admin group must login in order to view the roster.
Also, this would help with hiding the guild bank from non members of the guild. So only Logged in people who are in the members group of phpbb2 could see the bank contents.