to actually adjust the valve clearance you will need a decent 8mm wrench and something to turn and hold the tappets with. You can buy the Suzuki tool (no) or make a tool from a square drive cabinet screw (#4 I beileve) and some kind of handle. I used the handle from a small screwdriver, Paul used something clever, I can't remember just what it was. It was his idea so blame him!
Do yourself a favor and if you are using a set of feeler guages that are held together in a metal case, remove the ones you plan to use and handle them individually. You will have much better "feel" with the feeler guages.
Paul, do you have the tool tip posted anywhere?
Steve