Replacing the Steering Lock and Ignition Tumbler
Buying a car without a key presents a challenge. You can lock it, but you can't unlock it. You can not start it. In this case, the immobilizer/central locking unit module under the driver's seat, was corroded so badly that even if the car had a key, it would not have functioned. I bought a matching set of 3 keys, steering lock, immobilizer box, and DME for about $500. The challenge was, how to get the tumbler and steering lock out.
Edit: First step, remove the instrument cluster (mine was already out). See this article and be very careful with the brittle connectors on the back of the cluster:
https://www.pelicanparts.com/techarticles/Boxster_Tech/90-ELEC-996_Cluster/90-ELEC-996_Cluster.htm
Remove the side vent and headlight switch.
Disconnect all the wires from the ignition and steering lock.
Removing the tumbler: Pull out the rubber surrounding the ignition tumbler, then use a chisel to bend and crack the soft cast aluminum that holds the tumbler. Eventually you will be able to pull it out.
Remove the steering wheel: If the steering wheel is locked, you should now be able to push in and turn the ignition with a screwdriver to unlock the steering. Fully loosen the 2 captive screws that hold the airbag and remove it. Disconnect wires. Mark the steering wheel and shaft so that you can reinstall it in the correct position. (24 mm nut and washer.)
Remove the rest of the stuff that's in the way of the steering column. (Small screws and gently prying.)
Remove the bolt that holds the steering lock (10 mm) and the screw for the bracket over the ignition switch.
Push the release button on the steering column where the steering lock connects. It should easily depress if the steering is unlocked. Slide the steering lock out.
Reverse the steps to install the new one.
In my car the release button wouldn't move. Something was stuck. I tried various combinations of screwdrivers, rods, and hammers. Nothing worked and at one point I bumped the windshield with the back of the hammer. As a last resort, I used a drill to drill out the button. When I started drilling, the button popped down and the steering lock started to slide out. The drill must have scared it more than the hammer.
Installation was easy.