A browser ... ?
Ahh, so I totally didn't think I was going to even try to do this ...But epub needs HTML, and I found CSSBox, and well one thing lead to another ...
So I've basically ported the SimpleBrowser example from CSSBox to ReaderZ - all it can do is render the page, and it lets you pan and zoom as with PDF files. No links or anything.
I tried rendering on the fly, and into an image - the former is a little slow to scroll (but not far off the e-ink speed), but I don't think it's clipping the drawing regions properly and so doing a lot more work than necessary anyway. Using an image scrolls fast but can't be zoomed very well, and takes more memory (I blew it with boycottnovell) ... so trade-offs.
It's pretty slow and clunky, but what can one expect when XML is involved?