That should be two rings. The lower ring, which touches the spring, is what you physically adjust the preload with. The ring right above it is a lock ring. Loosen this ring first, then adjust the lower ring. Don't forget to tighten the lock ring.
I have an 08 GSXR 600 shock. It required cutting the toolbox, not the battery box. Just stuck the tools in the "trunk." You really should check your sag before you start cranking on or off the spring preload. Look at the threads on the shock and you'll see which direction to turn it. Clockwise increases preload. Counterclockwise descreases it.