[Zope] conditionally caching zope

Hi, Currently our Zope setup (http://dot.kde.org/) can't gracefully take the full brunt of our site hits, so we are using an Apache proxy/cache solution which works very nicely. For many pages however, I would like Apache to send cached copies IF a certain cookie is NOT set, and otherwise, query Zope for a dynamic page. This tactic would enable us to handle Slashdotting while not losing the settings of our regular readers. Has anyone done this before? Any suggestions? Thanks, Navin.