I installed one of these yesterday and great piece of kit. Home - www.hexezcan.com
It's from the makers of the GS911 and works off the bikes canbus.
You connect it to the battery of the bike then the canbus connector on the RDC module. I used one of the channels for my Stebel horn and it allowed me to remove the extra wiring and relay. Since it reads the canbus signal for the horn it actives the lead when you push the horn button.
You can also connect lights to it and set functions like strobing when the horn is pressed and one light will turn off when the indicator is used.