There seems to be a shortage of instructors world wide at the moment. I am not involved in instructing in Aus, so take this with a pinch of salt, but usually cities like Melbourne or Sydney have enough applicants to fill the positions without needing to sponsor people. Go bush and the story might change, I know that China Southern are short, but thats in rural WA...
I know that you said temp visa, so again read into this what you want. But a few years ago pilot qualifications were taken off the skill list for perm visas as there is no shortage of pilots over there.
As I said, I'm no longer over so take the above with what you want. Just remember, where there is a will, there is a way...