What you do in this case if have the parking brake on to hold the hubs stationary, then you borrow two helpers - one is attempting as hard as they can to turn the inner wheel clockwise or counter-clockwise (your call, don't really matter), the other helper does the same with the outer wheel but in the opposite direction, and in the mean time you run the lug nuts in and tighten them - when you get four of them pretty tight the helpers can let go of the wheels and let you finish torquing the lugnuts down properly. What this accomplishes is centering the wheels on the studs, as your helpers are forcing the wheels against the studs the studs will all set into the middle (radially) of the stud holes in the wheels - they will however be against one side of the holes, which is why you have the wheels forced against the studs at opposite directions. This is how I install my outer wheels, my inners are where they should be but I have 5/16" spacers between the inners and the outers which are just thick enough to where the outers no longer ride on the hub flange and so a not hub-centric anymore - I do this by myself and I use an impact wrench on a low setting to run the lugnuts initially, it's a bit of annoying but t works great, I have no wheel vibrations whatsoever.
He shouldn't have to worry about the outer wheel with shanked lug nuts though, just the inner. The one thing you MUST check is that the shank doesn't go completely through the wheel and contact the flange or wheel behind it. If it does, even by the tinyest bit, your wheel will not be tight even if the lug nut is
And yes, if it's just inner or just outer wheels that need to be centered then it's a one-man job (tho a helper is still nice), but in case of both inner and outer wheels being off the hub lip then forget it, you'll need the extra pair of hands for sure.
