To get the Gale Boomerang you need to enter the temple and go north until you reach an area outside, walk up to a bridge and a white baboon with the boomerang will destroy the bridge, after that go through the temple until you find 4 monkeys:
(for the forth you must hold the bomb spider creature until it glows red, then throw it, then it should explode in mid air taking out the boulder, timing is everything so it may take a few tries).
Return to the outside room, the monkeys will make a chain accross the broken bridge, enter to be faced with your first miniboss:
This guy hops about from post to post and will throw the boomerang at you, jump / backflip out of the way then roll into the pillar he's on (you might have to roll twice i can't remember) anyway he will then fall on the floor, slice and dice him until he gets up. Repeat the process until he dies - leaving you the Gale Boomerang.