hi heather,
the hospital gave us a brochure that states'in nsw you are required by law to use an approved child restraint, in safe condition and correctly fitted and appropriately used' so i guess you can fit it yourself ? but there is a company that fits car seats from the royal hospital for women car park. i am getting mine done tommorrow and they said that it costs between $10-$30 (usually $20) and they are RTA approved. we were going to put in ours ourselves but it seems quite reasonable and we thought at least we know its done properly.
hope this helps