Not to be a downer; but I would be cautious about attempting to design too much of an "interface" on top of an ebook. Now, I understand if you simply must DRM this or something, that you'll have to use some sort of obnoxious Etext reader software; but if you don't, I'd give serious consideration to keeping things simple. A basic PDF(with links for navigation, if you feel like it) is readable on pretty much anything, quite printable, and won't induce your readers to want to gouge your eyes out. HTML is, if anything, even more widely readable, and easier to manipulate the text of, if perhaps less trivially printable.
If you were feeling deeply nice, a simple CD with nothing but a suitable autorun.inf which would bring up a basic splash screen offering the user a choice between standard formats, PDF, HTML, Postscript, etc. with those documents also in sensibly, clearly, labelled directories(for the folks without Windows autorun) would be lovely.
http://autorun.moonvalley.com/autoruninf.htm provides a description of the autorun syntax.