Steering wheel Alignment
What I'm not all that clear about is the centering screw/mechanism/procedure for getting the steering wheel (rack?) centered first.
On the front side of the steering rack housing, opposite the point where the steering shaft enters the rack, is a colored plastic screw (it may be a metal screw on some cars). If you remove the screw, you can see the actual rack inside the rack housing. There is a dimple machined into the rack, and when the dimple is centered in the open screw hole, the rack is centered.
With the rack centered, you can check the position of the steering wheel, and center it if needed by removing it and repositioning it on the splined shaft.
With the rack centered, the wheels should point straight ahead. If they don't, you can set them by loosening the lock nuts on the tie rods, and turn each tie rod exactly the same amount in the same direction as needed to straighten the wheels. Don't forget to securely tighten the lock nuts.
There is a Porsche rack centering tool, which is a $2.25 bolt that screws into the open screw hole, and has a pointed end to lock the rack in the centered position.
Don't forget to reinstall the plastic screw to seal the hole when you are finished.