It is not possible to register a vehicle to a private interstate address.
You will buy the car in Vic and go into their motor registry, cancel the rego, hand in the plates and pay for a temporary permit to drive from Vic to Qld.
Once home it will be an inspection and go to the motor registry with fist fill of paper and pay them money.
That's the official way
.
Alternate is to buy the car, drive home and do all the Qld rego stuff and hand in the plates when you get here.
If you want to stay (probably
) legal and the seller is understanding, just get the receipt post dated so if you do get in trouble you can claim that the car is borrowed until such time that you get home.