If you have some sort of rack setup, you can get the Monokey mounting hardware from Twisted Throttle. Basically, you get the two posts and the "pyramid" that can be bolted to virtually anything.
Something like this, I think:
1983 Suzuki GS850G, Cosmic Blue
2002 Suzuki Vstrom DL1000, Midnight Blue
2005 Kawasaki KLR650 - Turd II, The ReTurdening
"Do not crinkle your food wrappers loudly. Be considerate to others, or I will bite your torso and give you a disease."