Hacking JD-800 wavetable?

[Grant Richter]

I recently got a Roland JD-800 keyboard and service manual in a trade.

The manual shows the PCM wavetables as 3 x 8 megabit mask ROMs. It should be
possible to replace the wavetable with 3 x 27C8001 EPROMs but I have been
unable to figure out the PCM encoding scheme used in the wavetable. (I tried
all the usual raw PCM formats)

Anybody have any information on this? My purpose is not to take their
wavetable, but to put my own in. I love the prettiness of this unit, but I
want to put in more strange loops and different types of wavetables.

Does Roland have a proprietary encoding scheme, and are there any software
utilities (perhaps for the S-50) that move between open .wav or .aiff format
and the proprietary scheme?

Thank you.