I just did one on my 97 Grand AM and it took me about 6 or 7 hours to get it done, and what really pissed me off want the easy to do it when I finally figured it out. One thing I learned (not true w/all cars but most I know of go like this. First you will have to take off the housing around the steering column. After that you should see on the part where the Key goes in, if you look under there is sometimes a little rectangle type hole with with a the tumbler lock. In almost all cases that I have seen and what it was that pissed me off was because my tumbler and key was not able to turn to the on position.
Well after getting the key and tumbler to actually turn to the on position all I have to do was push the little rectangle thing (under the housing that the tumbler goes into. If there is not the little rectangular thing like I was talking about you might want to look around for some type of what they call a set screw which will be on the outside case area of where the tumbler actually inserts in to the steering column housing. Remove the set screw and the tumbler trying to pay close attention as how it comes out that why you will not have any problems.
Well after getting the key and tumbler to actually turn to the on position all I have to do was push the little rectangle thing (under the housing that the tumbler goes into. If there is not the little rectangular thing like I was talking about you might want to look around for some type of what they call a set screw which will be on the outside case area of where the tumbler actually inserts in to the steering column housing. Remove the set screw and the tumbler trying to pay close attention as how it comes out that why you will not have any problems.