Here in Australia, to register the bike you have two options:

a) Buy one that was complianced by a company. Our registration requirements means that vehicles need to have an ADR (Australian Design Rules) ceritifcation, commonly known as a compliance plate. There are all sorts of places you can buy a complianced bike from.

b) Private import. I haven't done this before, it takes a bit of time and money. There are links to how to do it (varies depending on where in Aus you are going to live). Basically, prove that you have owned the vehicle overseas for over 12 months and pay a lot of money.

I hope that helps.