Yeah, the dummy is just inheriting rotation from a higher level of the hierarchy, so technically it is not rotating when you work with the foot. It is just inheriting position/rotation information, but this is not passed down to the roll bone. Hmmm... Hang on, I'll experiment a bit.
About 9 months ago someone here helped me gtting a roll bone system workign in Max5, using bones in conjunction with biped. Max 7 has it built in, but I want to add it to the feet, and maybe add some other bones. It's just working out the way I *THINK* it should work, so if anyone can shed some light on this it would be…
I'll give it a go, but I've found that in max7 there is a special helper. I don't have max here, but I beleive it's *something* like TMExplorer. It's in the helper menu. Anyway, that can inherit the rotation from the ankle bone, and then the wire parameters work.
OK, got one solution. Add the twister bone as you have done, then assign a Look At Constraint to its rotation with Keep Initial Offset checked, and pick the Biped's toes. Link it to the leg. Now when you pivot the foot, it should turn. This what you were shooting for?