How do you beat Belloq in Lego Indiana Jones 2?

You need two players for this. There are three jungle cutters: One you currently ride, another a soldier is riding and the last one Spalko is riding. While you are on a jungle cutter, have your buddy defeat the last 6 cars until Spalko appears. While riding the Jungle Cutter, hit her in the back and you'll complete Rainforest Rumble.