visa requirements??

Hi,
My name is Joseph Mok. I am an Australian and my wife holds a Malaysian passport. We resides in Sydney Australia. We are joining an Asian cruise from Singapore whereby there is a stopover in Hong Kong. We would like to join a couple of land tours while we are in Hong Kong. Do we need entry permit to enter Hong Kong? If yes, do we obtain it in Australia before leaving or is there other ways of doing it, i.e obtaining the entry permit.

Joseph Mok