I think the best way is to make sure the cats have a "dog free" zone. I've used a baby gate to block off my basement and made that cat territory. Especially make sure that the dog does not have access to the litter box! Dogs love those little "appetizers" they find in the box from what experience has shown me. I learned that lesson the hard and disgusting way.
You also have to be especially careful since an aussie is a herding breed, and could be tempted to use them as practice. Make sure your dog is on a lead when they are all introduced.
When I introduced my dog to the cats it was touch and go with Sophie--she had been running loose and fending for herself for who knows how long and just wanted to eat them. It took weeks of having Sophie on a long leash and hundreds of corrections before she learned her food was in the bowl and the cats were supposed to be in the house, not her tummy. With my other two brought home as puppies, there were no such problems, but the cats DID sulk for about a week.
And eventually the cats have learned to accept the fact that there are dogs in their house. I'm not sure they like the idea, yet, but they at least tolerate it.
