Hi Juno, when are you planning on coming to Australia? I have taken overseas students doing placements before. At the moment i am pretty right for team members and i get asked by many people each week for work. Melbourne is a good city for tree work. I am sure you will find a company that needs someone and willing to give you a go. Try this link to find someone.
http://www.yellowpages.com.au/search...+VIC&stateId=2
Good Luck. And if you end up here and something falls through let me know and i'll see of we can help you out.
Cheers
Trev