The easiest way to do this is to just create a separate button for the horn on the steering column. It's way too complicated to figure out how to make the horn work when you're using an aftermarket steering wheel, especially the MOMO from the JZA70. There are a few people who got the factory horn to work with an aftermarket wheel. But to save you the headache, make separate button. It literally only takes 15 minutes to do. Here's a picture of my NRG quick release hub and a red horn button.