Actually I had a look in the gnash folders...
/mnt/us/extensions/gnash/lib/gnash/libSDL-1.2.so.0
which leads me to believe that this will automatically work once we have a fixed SDL build. the main app (gnash) would need rebuilding with an SDL rendering target...
my build currently has TSLIB support, ALSA, and a slightly updated video section (work in progress)
If someone has a better one with ordered dither already implemented I would happily fork that into what I have and share it.
I'll play around with updating the Gnash SDL and see what happens
EDIT: SDL only handles the sound in this build...
Need to change rendering targets.
from my testing it is DEFINITELY not managing the eink properly, and a move to 2 bit would certainly speed thing up. (The output is near identical to prboom with default colours, for sure a colours issue)