Here's some info I saved. I didn't write it and have not had to do it. Roger Fuller wrote the main
part.
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If it’s like a 57, the horn rim comes off with a bit of a press and twist motion. Remove a nut, and use a puller to take off the wheel. Switch comes out with a couple of screws, and you have to fish the wires out. They disconnect right under the dash.
Roger Fuller
Use a pull string or wire to follow one of the old wires up the column. Remember to unscrew the telescoping hub all the way and push it back. There are 3 screws holding the chrome hub to the column. One of the screws is behind the signal switch. Remove these 3 screws also so you can get at where the wires come out of the column and into the hub. There is a sleeve in the column that the wires go through It is only about 1/2 x 3/4". There is only enough room for not more than 2 bullet ends of the wires at a time. I stagger them and use 1 layer of blue painters tape to hold them together. Thread them through the loosened hub and down the sleeve in the column. Push them in as you pull on the pull string or wire you already prepared. I've done it several times, it works for me.