I just received my tool tubes. I will be mounting one either side. Underneath the original exhaust. My plan is to mount them on the inside of the SW Motech pannier racks. The bottom mounting hole will fit nicely on the bolt holding the front bottom slot ring. The top mounting holes will be attached to a small alu triangle that I will be attaching to the rear bottom slot ring and the L-piece where the panniers are locked to the rack.
When I get around to actually doing it I'll make some pics to make the idea a bit more clear.