No Jumpseat Agreements here...
Unfortunately BMUD, jumpseat privileges are not available in Australia.
I flew for a Part 121 carrier in the US for many years and really miss the CASS jumpseat system. (So does my wallet - in comparison, staff travel is VERY expensive)
For over 10 years I was looked after (nearly always in First or Business) by crews from across the US aviation spectrum. That courtesy and friendly comradeship that was extended with a warm (and free) welcome into a comfortable ride anywhere on that carriers network is something I wish we had in this country.
Being able to extend a free ride to a fellow aviator is something the US industry should be very proud of.
Alas, "ownership" of the jumpseats in Australia by the flight deck was lost many years ago. Unfortunately there is just not enough will or pilot union political clout to ever enable a US-like jumpseat system here.
As previous posters have noted, ZED fares and interline tickets are the best you will do. Fares on the low-cost carriers are often cheaper than this and are obviously confirmed rather than space available.
Hope you have an enjoyable visit.
PG