Here is a member who has the body lift installed maybe he can chime in @Touchdown
http://www.thenissanpath.com/viewtopic.php?t=18419
He also has suspensions mods.
As far as the body lift install the pucks go between the frame and body mounts.
I have helped do Xterra lifts I would recommend searching some the their forums also they have more detailed instructions. In a quick review I do remember specific tips.
Do one side at a time.
order all parts before you start. Different Radiator hoses coolant.
the body lift on moves the body up so the suspension stays the same so no alignment adjustments needed. but the steering does move just not 100% sure on the details.