Mechanim - should be simple, but...

Ok I'm new to Mechanim but I've been over the docs and tried a bunch of stuff, I'm lost.

Have a humanoid that I want to just kinda sit there. I have no animation defined, that is no curves. I have hand IK targets. Think of this as a guy sitting at a work station just moving things on a console in front of him. So I move the IK targets a little. For the hands, this works just fine.

What's killing me, his feet go all hyper-yoga! I'm using the sample IK script that comes with Mecahanim tutorials, so I set the hand targets (again just fine), but no foot targets. I expect him to maintain the pose I put him in 'manually' by adjusting hips and knees and feet to get him in a sitting pose. And do nothing at run time. But his legs go crazy (not moving, just pretzled). I tried setting a Mask to turn off IK for feet and legs et al, no help. Maybe I'm not doing that right? I went to the controller (idle/run/walk sample), which never goes out of Idle of course, and set a new layer with the 'no feet/legs' mask. Also on the script, I set 0 weights for foot weights. Still no help.

Please help