Well, I come from using Animation Master, and am working with a crowd scene in Maya right now. The principals are the same.
What I'm doing is this: My crowd is a team of armyguys escorting a tank.
First, create a walk cycle. I made mine 48 frames, walking in place. Be sure to only animate the waist down.
Then I built some animation of the translation that syncs up perfectly with the cycle. (feet now stick to the ground)
I made this 2 times the length of the scene for offsetting.
Now I turned the leg cycle into a clip.
I turned the translation into a clip.
Then I built several differnt Torso movements. and baked each one into a clip.
Now in your crowd scene, you lay out your people, give them all the walk but now you can offset the walk, and speed with the clips. Add the translation clip, and now they walk around. If you line up the two clips you can cycle the walk, and offset the translation and walk, and you get beautifully animated offset walks.
now you can add your random torso movements and offset them and timewarp them to hide the fact they are all doing the same 6 things.
It worked out great only now I don't know how to bake the clips into real animation data.
The otherway would be to use a script. Have it constraint each partical with a pre-recorded animated character. Then just control the particals.
At anyrate.. if you find out how to bake a clip please let me know. 
Jeffre Dates
Animation Director
ReelFX Creative Studios
