[Zope] ZPublishing

I am trying to send some dynamically generated binary data to the output buffer. How do I do it in python with Zope? As I understand it HTMLFile(xxxx) returns a dtml document object. I could dump the data to file and then try to send it using the binary equivalent of the HTMLFile class. Is there such an animal? I noticed there is the ImageFile class, but the guess_encoding module does not list the content type I need to publish. Is it a good idea to add mine there or can I override this? Isn't there anyway I could just write to the output buffer? Thanks.