Look a the box as it will be installed into the vehicle, like this.

The Red arrow is the direction of the input shaft to the steering wheel. The Blue arrow is the direction you want to orient the firewall side input coupling screw. That way when you're installing that last bolt you'll be able to reach it without turning the steering wheel. (Refer back to steering coupling reference picture mentioned previously) Do not tighten down.
Attach the lines to the new box, you'll use them to pull the box into position. (You can only install them one way) To keep the steering wheel centered put the key in the ignition to center it and then remove the key to engage the steering lock. You may have to play with this for a bit to keep it centered. Or if you have the luxury of a second person, they can steady it by hand.
Get the three mounting bolts ready and put some threadlocking compound (e.g. Loctite) on the threads.
[The FSM directs installing new bolts each time, I don't believe this is necessary. Especially since you're just paying for clean bolts with threadlocking compound on them]
I'm not going to lie, this part sucks. You're going to get pretty intimate with your fender.
Thread the lines up past the IP and then from the top of the car, pull the box up into position. The box is centered so you just need to match the splines up on the steering wheel shaft while it's centered. At this point you need to maintain the attachment of the coupling on the input shaft while trying to position the box so that at least one bolt can be threaded in from the wheel well. Once you get that first bolt in the rest are quite a bit easier.
[If your steering is slightly off at this point due to the wheel shifting you can try again. Or if you're getting fed up there's another option. Finish installing the box and then remove the steering wheel and move it over one spline or two at a later date to align it with the box. A few splines won't hurt anyone.]
Thread the remaining two bolts in and tighten all three.(70-80 NM/ ~50-60 ft -lb)
Then move the input bushing enough up the shaft towards the firewall so you can thread the top bolt in. It sits into a groove on the shaft coming from the steering wheel, so you need to wiggle it until the bolt fits into that groove.