[Zope-dev] Overriding HTTPResponse.unauthorized()

I've got some rather funky auth requirements where I need to stop Zope from challenging Basic authentication when Unauthorized is raised. I seem to be able to do this if I monkey-patch HTTPResponse.unauthorized(), but what I'd really like is to be able to hook into it to make a user folder-overridable challenge with a fallback to the standard unauthorized. Maybe such a hook would be useful in 2.6 :-) So, given that, can I get to the user folder from HTTPResponse.unauthorized()? Or are there any better ideas?