As discussed above in this thread, for newer Kindle models it isn't really necessary to register with Amazon first. The "Update Your Kindle" menu entry needed for the downgrade to the initial factory build is there already right out of the box. No need to ever once connecting a brand new Kindle to Wifi before jailbreaking... You see: Shit happens...
BTW: My friend just confirmed that on his KT3 the jailbreak survived the 5.8.9.2 update without any trouble...
