This page at Customs might help ... http://www.customs.gov.au/site/page6091.asp
I understand that you need an Express Courier, but it seems that it would be good to talk to someone at Customs in Sydney.
When the goods come into the country, they actually are stored at a 'warehouse' that you advise until Customs releases them to you after checking. So I think that's what they are referring to.
Customs phone number is Enquiries
- 1300 363 263
- +61 2 9313 3010 (outside Australia)
8am to 5pm (AEST) Monday to Fridays excluding national public holidays http://www.customs.gov.au/site/page5834.asp