As someone else from DJ said to you on the other site where you posted the exact same question, yes it's possible as
VB staff travel isn't based on seniority.
The only questions you've got to ask yourself are:
1. Where will you stay when you need to be in SYD (reserves or night before early departures etc) & how much will this cost,
2. How much will the airfares cost before you have staff travel access,
3. How much will staff travel cost,
4. How much will it cost long term as staff travel won't always be an option due to loads - what will happen if you get offloaded etc.
5. How do you feel about extending your day - so leaving MEL to get to SYD while the SYD based staff are still in bed resting for the flight & then spending 16 hours plus on duty after that. How fatiguing will that be long term.
V Aus isn't paying a great wage for CC so you'd have to ask yourself if commuting will be worth the expense (both financial & health) in the long term.
I commuted for almost 4 years & would only consider doing it again if I was on a commuting contract with the airline - it wasn't worth the extra stress & money.