Basically he'll need to put it through three separate processes. The first one is to get it inspected by an engineer who issues VASS (Victorian Automotive Signatory Scheme) certificates, so they can inspect the repairs made to the roof, and certify that they're done correctly.
The second process will be getting it complianced, which means getting it inspected to make sure it meets all the relevant ADR's, and fitting a compliance plate to the firewall. I don't know much about this process, maybe VASS engineers can do it, or maybe someone else has to do it. A Landcruiser from the UK will probably pass with no alternations, but some vehicles from Japan etc. need minor changes to lighting (the way driving lights are switched, adding instrument light dimmers etc), some need side intrusion bars added to the doors, and some may need the seatbelts to be replaced with ones from an Aussie spec. equivalent model.
The third process will be to get a roadworthy inspection done. This is my area of expertise, I'm happy to answer specific questions but it would take way too long to explain everything that gets checked, what it gets checked for etc. but most of it is commonsense stuff. If the car fails, you get given a pink copy of the certificate, which explains what needs to be fixed so it can pass. You then get 7 days to bring it back for a second inspection (most workshops don't charge you for the second check) and if everything has been fixed, it passes and you get a green copy.
The best thing to do would be to go to a workshop that does roadworthy inspections, and ask if you can get a "safety check" done, which is the same inspection, but no paperwork, they just give you a list of items that are unroadworthy. You can then fix it all in your own time, and bring it back for a roadworthy inspection, knowing that it'll pass.
If he's anywhere near Ballarat we'd be happy to do it for him.
for the trip... but then again I know where I want to go next as well...
