Basically (if the poles are still open in Melbourne, which they should be) you phone the pole number of the ABC and follow the prompts or SMS you're favorite song to the same number. Unfortunatley I don't have the contact number, I'll try looking on the ABC web site, to see if the pole is still open and what the contact number is. They've done this for my favorite film and my favorite book, I voted for the LOTR triology, which one in both catagories :-)
I'll try the ABC web site now....
Take care,
B.R