[Zope] HTML post processing in Zope

Hi all, I am trying to perform a post-processing on all HTTP responses, before they get sent to the browsers. I am using Zope 2.7.3 nad Plone 2.0.5. I had a look at the ZServer class: it seems to be the right place, but I don't understand all the code there and I am afraid to break something :-( Am I on the right tracks there? Could someone with great Zope knowledge be kind enough to point out which method I should change? (I want to change the HTML content, not the headers). Any pointer would be appreciated. Cheers. Cyrille.