My dealer recommended using AutoCom's Part #158 switch for the AutoCom. He said it cuts down some of the ignition noise as well as the noise from the ABS system. Same is stated in the manual that came with the AutoCom #158 switch which was designed for the BMW Can-Bus system.
Their switch box is wired direct to the battery, a trigger wire to the accessory socket +12 lead, and the output + and - leads go to the AutoCom. Doing it this way helps to cut down on troublesome ground loops as the unit lifts the ground side of the circuit from the bike frame.
The AutoCom part number is 158, called a "Direct Battery Connection, Fused Relay, Remote Triggered, Power lead." Don't know the price.