Mental Ray Anti Aliasing:

I don't know if you guys are running Maya 4.5 or 5, but in 5 there is a common tab that has the resolution for all the renderers. As far as MRfM anti-aliasing goes, you can find it under the sampling quality tab in the render globals. For the contrast tolerances, lower=better. And the two value sampling input is like the min/max shading samples for maya. Try 0,2 for general stuff and 1,3 for final renders.

Josh