Have you tried operators outside of Darwin?
As mentioned Kakadu Air is one, though they usually look for around 350+. AAA, Gumbys, Katherine Av, Lajumanu Air etc etc All of these have been known to take on green pilots.
The majority of the operators operate their twins VFR, as far as I know only Chartair, Hardys and JFC actually operate their twins IFR.
Offer to wash planes, clean hangers, drive buses (get your LR and H endorsement) etc and you never know what sort of start you may get. I know someone who was just a baggage chucker for an RPT outfit and got a job on a turbo prop because the bosses took a liking to him.