Did the trip a few years ago myself. Did it in convoy with a mate of mine. We made it in about 5 days I think. Stopped at Cobar, Port Augusta, Alice Springs, Katherine and then Kunners. Spent a night in each place, except Alice where we spent two or three nights. Was about 4,600km from memory, so each leg was about 1000km so pretty big driving days.
Overall, pretty picturesque drive, a little boring in some parts but really interesting to see how the country changes. All main roads so you're not gonna end up in a place where noone will find you if you break down.
Just watch out for the cattle crossing the road!!! They're big - and will really modify the front end of a Sirion!!!