The Shimano Dura Ace tool, with the chain ring nut tool on one end and the two-pin dust cap tool offset on the other end, works most of the time, but is a bit awkward to use. The main problem is that you have three items to juggle at the same time, while keeping them lined up and secure. These tools used to come with every Dura Ace crankset, and since I've installed countless numbers of those, I still have a handful of them lying around. I have come up with one trick that makes these a little easier for stubborn bolts/nuts. I clamped the dust cap end into my bench vise and bent the tool into a right angle. Now when the tool is clamped in the vise, the chain ring nut side is pointed up and secured by the vise. While holding the crankset in one hand, I can position the nut onto the tool and use an allen wrench in the other hand to loosen the bolt. I actually use an allen socket head attached to a small (10 inch, maybe) handle, to get my hand a little farther away from the big ring. I also wear mechanic's gloves for the operation, just in case.
Wayne Bingham
Lovettsville VA