Yeah, MH would be useful, but I think it's November when they're tipped to join OW so I guess it's an unknown quantity regarding their availability.
Another option would I believe be Air Berlin, if you head across Europe, but their HKT timetable doesn't seem to be out for Jan '13 yet.
(PS Darwin isn't in WA, it's the Northern Territories, but with no direct flights to Broome from Singapore, you'll probably have to go via Darwin anyway...)