Short story - they make sure the car meets ADRs.
Long story - things like adding an unleaded fuel filler restrictor, rear child safety restraints mounting points, new charcoal canister and catalytic converter (if required), new tyres, etc etc.
In terms of steps, once done, you just follow VicRoads procedures for establishing new vehicle registration for an import:
http://www.vicroads.vic.gov.au/Home/Regist...egistration.htm