Pulling up the owners manual for that radio (manual here)
it appears that the extra receive only channels can be programmed from only between 403 to 520 MHz. Your local police departments would have to be using frequencies in that range, and only on analog FM.
You may want to make a post in the Australia Radio Forum
here at RR, but unfortunately it looks like there has not been any activity in that forum.
I'm not sure how friendly the police departments are there, you might have some luck contacting the police departments and asking if they can provide you the needed frequencies to listen in.