@knc1: I think it was on a K4, with its weird not-really-a-K3-but-not-really-a-K5-either kernel module.
@twobob: There was an (old) tool called fbgrab that was built for that, but AFAIR, it didn't support the fb format used on the Kindle. I also vaguely remember someone doing a quick'n dirty C (I think?) version of something similar on a GitHub project. (Whoo, vague hints galore!
).
EDIT: Eh. I think that's what you were referring to
here .