Here's a method I've used to adjust the clutch cable, it's considered 'wrong' by most people that work on BMW bikes, but it works for me.
Adjust the handlebar adjustment to get all the 'slack' in the cable you can, I think that is in all the way, loosen the 'jamnut' on the adjustment bolt at the back of the transmission, and back the adjustment bolt out, to where the arm has a lot of freeplay.
You should be able to remove the cable from the arm on the transmission, with the cable removed adjust the bolt at the rear of the transmission to get about 1/4 inch freeplay movement in the arm, measured at the end of the arm, tighten the jamnut.
Reconnect the cable to the arm, then go to the handlebar adjustment, and move the adjuster to get about 1/8 th inch freeplay at the lever, that should get you pretty close on adjustment.