[Zope] - tree tag questions

I have two questions regarding the tree tag: 1) How do I force the tree to only display the branches I want? specifically I want to eliminate the 'Control_Panel' and 'acl_users' branches. 2) How do I force the tree to render in the context of the particular directory? I'm including it through a document called 'sidebar' in the root, and although I want it to be acquired throughout the site, I would like it to display the entire tree, and not just the branches below the current document location. Thanks, Michael Bernstein.