Probe this:
3) The archive fb2.css save as fb2.css and rtf.css and htm.css and copy all together
2) There are firmwares that the fonts work in the SD and another firmwares that work on the internal memory
This information are in the Spanish's:
http://www.lectoreselectronicos.com/...t=666&start=30
(Apologize for my little english)
I wish you can do.
Regards of
José Javier