[Zope] image caching

I have a class that wraps images and I want to be able to set the HTTP headers for the object when it is requested. Which method do you need to override in my python product to catch all requests to that object? Currently the structure is set up such that I have a Picture object and in its dict I store a regular zope Image object. It also stores a thumbnail and a good bit of other information. I want to override however that image gets handed off to the browser or to the rest of zope. Designing the webpages of tomorrow http://webme-eng.com Designing the MMORPGS of tomorrow http://worldforge.org