Thanks, Pete330!
I can confirm it's working on my freshly jailbroken PW3.
Only:
- Images(where present) show up in smaller size due to the higher resolution of PW3
- After quitting a game, A further 'enter' is required to get back to the kindle main screen(wasn't required in PW1)
- Keyboard seems smaller (this is the default kindle keyboard used by all apps, i suppose)