Ford Think Horn

Just got a ford Think that was pretty much all done. It had a new aftermarket multi-functional unit installed a few years ago. All the accessories work fine, except for the horn. Evidently, this rebuilt multi-functional switch/unit supports every except the horn as some others have also noted.
The fuse is good and the horn relay does make a clicking sound when the horn button is pressed.
Is there a way to use an aftermarket horn kit that would not jeopardize the integrity of the electronic components. Most horn kits are 12 volts. I was hoping to find a wireless remote unit that had a remote switch that could be attached to the steering wheel. Any thoughts/ideas?
Thank you Bob