The official converter is the Xylog Parser DLL provided by Sony. You can download it from
www.prslabs.com (needs free registration). It is used by e.g. lrs2lrf.exe I made a few years ago.
You can also try some other tools for LRF generation from
here. However, most of them are old and produce LRF files for Librie which are not always handled well by Reader.