2-Saw,
I'm pretty sure the tool is the same for a standard Honda caliper, and should be available at the Autozone type store.
In the past, (not on my NSX) but other Hondas, the tip of an open end wrench (12-15 mm) will fit into the groover and a crescent wrench to turn it has worked. Not very pretty or efficient, but did the trick. Remeber to loosen the bleeder screw to allow the brake fluid to go somewhere.
Miner