Been through all this with the m/bike club I run.
You will need to be a member of a car club that has a permit scheme and have your car inspected by the club's safety inspector or a current RWC. with the new rules they seem to have come down heavy on modified vehicles, our inspector was told that they have to be as close to standard as possible.
Costs are $64 for a 45 day permit and $114 for a 90 day permit. These come with log books and if you get caught driving without it filled in it is the same fine as driving an unregisted vehicle.