Kowa and K&L have an entire set of locknut tools. About $120. In the set, they all come in little bags with Honda part numbers in them. Might be worth getting you hands on the Honda special tool catalog.
You only need to know this one web site for unique must have tools. I had a steering head tool from them when I had my '02 R1 and is the best thing to ensure longer steering head bearing life, especially if you stunt.