I'd use mod_proxy/mod_rewrite over CGI anyday.
Would be interested to know if this behaves as you expect with that...
I see a lot of people having problems with PCGI setup. I think mod_proxy/mod_rewrite + VHM solution is far superior over PCGI solution and most people should try mod_proxy first if they don't have a real reason to use PCGI (btw, are there any reason to use it instead mod_rewrite+VHM?). Unfortunately, doc/WEBSERVER.txt coming with any Zope version discusses only PCGI/FastCGI setup so most people haven't a chance to try a better way first. So maybe we need to make changes to docs coming with Zope to reflect a new ways of making Zope works with Apache? Also, i think some docs on zope.org discussing SiteAccess, PCGI and FastCGI should be marked as obsolete with links to more modern howtos. This will make newbie life much easier.