Meat bomb,
As kwikenz said, best bet is try Bristow, CHC also have a SAR base at Pearce Air Force Base which is commuting distance from Perth.
The police most probably won't have an opening for a while (chatted to the chief pilot yesterday).
There are a few single jobs going in and around Perth. Helicopters (Australia) might be a good start as they have twin IFR operations in Gove N.T. which is a touring position.
Also give Jayrow helicopters a try they have operations in Karratha which might start touring.
Good luck.