https://www.mobileread.com/forums/showthread.php?t=88004
There.
Jailbreak... its' all on that one thread enjoy.
EDIT: whoops...
The JB for the 4 is on the wiki.... but TBH I would use:
https://www.mobileread.com/forums/sho...d.php?t=206064
That does 4's now. enjoy