Their website is misleading then. Their list of supported format makes it seem as if it should be able to read PDF files:
http://www.lexcycle.com/supported-formats
I did see mention of a PDF reader called "Good Reader" which does support these things, but no, it's not free.
I actually already made HTML and ePub versions of the same book, but it's nowhere near the same quality as the PDF. (The book in question is full of mathematics, and it looks a lot better when made with (pdf)LaTeX -- out of curiosity, I tried converting the PDF to ePub in calibre and the result was an unreadable mess.)