The 5.5.x/5.6.x firmware has been out for about 6 months, we do have posts on the subject.
Near the top of the index page list, just below the last blue bar ...
Select: PW2 from the drop-down list of models, click: Show Threads.
That might be a better place to start than in this K5 thread.
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Hint: Abandon thee all hope unless you want to use the serial port to install the jailbreak file.