I would be interested in knowing how to do this myself Alex.
Write-up and photos please.
sorry no photo`s(camera is broke)
since i was changing my air filter, thought it would be a good time to adjust the steering box. after i had air filter out, proceeded to remove the I/C tube, battery and battery tray on that side(this also made it easier to get to the ps pump for removal and installation), to get a clear view of the steering box top. you may also want to remove part of the shroud that snaps on. it will make really easy access to the jam nut and set srew....
once there, loosen the jam nut(3-4 full turns) with a 5/8 wrench while holding the set srew with a 3/16 allen wrench. then you turn the set screw clockwise till it is snug(not to tight) and back it off a 1/16 of the turn. while still holding the set screw, tighten the jam nut and reassemble the rest....
i will try and find some pics of steering box....
KRISTOLSON also has a good write up about this. look in 6.0L POWERSTROKE engine and drivetrain section..."steering box gear mesh"....he describes a different way of getting to the steering box for this adjustment....hope this helps....