So the idea is that if you are using keyboard+mouse, you use WASD for direction you want the monkey to turn and then Mouse 1 or 2 for how hard you want him to turn/accelerate. If you have a xbox controller it's same idea but with the left stick for direction and A-B-Y for strength.
However we are noticing that you might have to push the buttons a lot to get the intended effect. This is a problem we are encountering and are working on solving soon hopefully :D
Sorry about it though =<