Here's a MUCH quicker video about rigging an IK leg with a "no flip" pole vector. I'm definitely on more solid ground with rigging stuff than the Mental Ray stuff :)
Anyways, the idea is to create leg rig with a "knee twist" attribute so that you don't have to animate the pole vectors (most of the time). I prefer animating this way- a bit cleaner and works better for me most of the time.
Maya Rigging: No-Flip-Leg Pole Vectors from zeth willie on Vimeo.