Call for testers:
If you happen to have a 'new' K4, the current git tree *should* support those. I've just repacked my stuff to handle both K4, shout at me if it actually works and/or breaks on 'old' K4.
Depending on if it works, and when new infos about the PaperWhite(s) will drop in my lap, I might do a new release soon.
EDIT: Yup, K4B support's good