Simming is you friend for this one, not that it would be too difficult playing the matches - for all of the "Win the.......Competition" I found it easiest and quickest to select the top three teams in each competition to manage and then sim every game.
Set the difficulty to Very Easy to ensure victory too. Doesn't matter which team of your three wins, you still get the trophy at the end of the competition.
For this one just select Australia, New Zealand and South Africa (poor Argentina) and Sim Sim Sim!