He can always do it the way they did in starwars and use a bazillion q-tips painted various shades of pink supported through a screen and then they recorded footage while sweeping a brush underneath to make the q-tips undulate like a crowd.

As I recall they used the same technique in the movie Ben Hur and that is where ILM got the idea.

Just some ancient tech fun facts.

BTW I do not even know what Massive is Jay but it sounds scary Jay!