I got got around to installing the horn button I got from Jaime. It was very easy to replace the existing Nardi button that I had installed a Momo P emblem into.
I did have to add a ground wire, but that is due to the hub I'm using, not due to Jaime's button. The hole in the hub is too large, so I've installed some flexible plastic. The plastic prevents the button from grounding to the column. The wire bolts to the hub, competing the connection.
Pictures are 1. Wire and 6-32 bolt. 2. Installed wire. 3. Before. 4. After.