Spend 30 years populating the area around your house with mature gum trees, and then making sure that some of the trees develop nesting hollows. Then take care that nobody in your area overuses rat bait and ends up wiping the owls out through second hand poisoning. Put a leash on that feral old farmer two blocks over who routinely shotguns birds of prey out of the sky because he thinks that they kill lambs, and because the Dept of Environment are run by a pack of National Party hacks who don’t believe in wildlife and who’ve let him get away with that for 70 years. Also, cull the introduced trees from your garden, cos they tend to have branches that are more close together than gums etc, which means the possums can take cover in dense foliage where the owls with their large wingspans have trouble following. Suppress traffic noise and artificial light as much as possible, as their senses are extremely keen and it disturbs their sleep & nesting.
Besides all that, they actually do range pretty widely and will go quite far into the city. I’ve seen a photo of one taken in Ivanhoe, and apparently one made it to St Kilda East a while back, and even Flagstaff Gardens once. But there’s a lot more possum-friendly environments out there than there is owl-friendly environments these days. The lack of old growth trees with nesting hollows is the major problem for them.