Always experiment with boyfriend's Kindle first.
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You should not need to install USBnetworking, that is for when (if) things go very wrong.
(not to worry, Kubrick works very well on the K4)
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I don't think that the K4 jailbreak bundles the MKK (old name: KUAL prerequisites).
So...
JB + KUAL prerequisites + KUAL + Liberator
should get you just what you want.