Why would you want it? I have seen some, from an old Indian, old European war era bikes to custom choppers. I don't see the reasoning why you would want one on a modern sport/touring/SS bike, unless your building a chopper Kat, where the handling would suck large farm animals anyway so, speed would be reduced enough to use it.
They are very simple in form. Shift arm, pivot and linkage. The engine design of the Kat would make it a challenge. Harley/ Indian motors are flat sided. Inline 4 motors aren't. I could see it being done on a RAT bike.

Second thought, you could get around the engine with a push/pull cable setup.
Third thought, you'll have to relocate the clutch actuator to a peddle.