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!
"If I have seen further it is by standing on the shoulders of giants." Sir Isaac Newton, 1675