Have you considered taking the entire column out ? Sounds like you are half way there already. There is a small flange with a bearing in it, mounted to the inside of the firewall with three screws, and the coupling of the steering shaft itself, which has a pinch bolt holding it together. This is under the hood. The two sections of this joint only fit together one way, so you don't have to worry about the centering of the steering wheel. If you have an air bag, things get more complicated. There are several precautions to take. Consult a factory shop manual for deatils.

Are you sure you can't get the key to turn. Try wiggling the broken stub as you attempt to turn it, and/or pushing it in and pulling it out slightly while trying to turn. If you get lucky and both halves of the broken key line up with the tumbler pins, you will be rewarded with success. With the key in the "on" position, push the release button on the lock cylinder and it comes right out.