I see there are quite a few tools out there to convert all kinds of different files to LRF, but here I come with yet another one
It's called Book Processor. It takes a source file as input and can output LRF and HTML. The source file can be created by hand, or from the original input file (as long as you have a program capable of reading the input file).
You can find the application, the documentation and an example book at http://stuf.ro/bp/
The project is in a pretty early stage, so do expect bugs.