"This may involve removing the horn wire, which is a project in itself."

IIRC, you don't have to remove the horn wire to pull the wheel. Just push any excess wire down into the steering tube, so that the horn contact is sitting on the end of the tube. Then find a suitably sized socket (or washer and socket) to place over the horn contact and use the socket as a base to set the screw of the puller on. You might have to go under the hood to the end of the steering box and gently pull the excess wire down inside the steering tube, in order to get the contact to sit flush with the steering tube inside the car.