There is usually a customs officer stationed at Cape Mail office in Epping (behind the casino) that can give you and answer or at least request further information. I haven't been out there in yonks so not even sure if you can still enter the premises.
You need a EUR1 certificate or an appropriate authorized exporter in order to claim preferential rate of duty on the EU/UK and EFTA columns.
Edit: on values under EUR600 the commercial invoice requires the following clause in order to claim preferential rate without requiring a EUR1...
Let's see if I can remember...
'91 Honda Civic CRX (miss this one)
'86 Golf GX (modified to 2.5l; monster fuel consumption; dropped dolphin shape M3's on the 1/4)
Mk1 Golf CTI (miss this one too)
Ford Falcon XR6 4.0 (N1 ripper)
Isuzu KB250 (famr workhorse)
Toyota Landcruiser 47 series (replaced...