Well, I didn't do more than just take it off and swap the perf shift button around. I guess you are interested in putting the button in? GM glues the performance shift button into the hole, so you just have to be careful and get it to pop out. Once you have it out, cut the plug off the end and pull the wires through. Then I traced around the button on my handle and dremeled away on it till it fit. I started small and then just trimmed here and there until it would just barely go in.
The wire runs in a little channel inside the handle. I found it impossible to get it to go DOWN through the channel, so I cut the wires close to the button and ran them UP through the channel. Then I just soldered them back together at the button and slid it all in.
Interesting thing about the knob is if you peel the leather off, it is textured like leather underneath. Looks almost the same just missing the stitching around it. I only know this because I pulled the leather off the old beat up one.