I have just released the final stable version 1.3 of libdjvu:
http://www.bibles.org.uk/libdjvu/
As for the base firmware --- I used the latest lbook.ua one plus I made some modifications to speed up startup, speed up update (removed unused programs, e.g. screen calibration is not needed for Hanlin V3 which has no touchscreen), fixed some spelling/grammar errors in both English and Russia menus etc etc.
If you want to use libdjvu.so in another firmware you have to copy arm-lib/libdjvu.so to wherever the libraries are stored in your version. In mine it is in /usr/lib of rootfs cramfs image. Also, to be on the safe side, copy the libdjvulibre* files (and symlinks) from my image as these I compiled myself and tested whereas some others may or may not work with my libdjvu.so.