Mmmmm ...
Think you'll find there is no "Australia Police Airwing" ... as such.
Each State police Service either has an "Airwing" or uses Chartered Aircraft as their individual needs require.
Police flying tends to attract the Ex-Mil pilots and as a result they often end up being "Ex-Mil old boys clubs" (which is often not a bad thing?) or you have to be "in the Job" and get then get in line for any vacancies that might occur.
Try the appropriate Police Service "home pages" of the state with which you might like to join.
Good Luck.