It was brilliant to be on the mountain in winter. We rented back country skis and skied to the summit. Although the Kosciuszko walk was completely covered in snow, we skied to Rams Head North, which is one of the few places where you get a view of the summit. From there we traversed to Rawson Pass and hiked up the final bit ('cause they were out of skins for rent).
The terrain on Kosciuszko is so undulating, that you can't see the summit or the base of the mountain 90% of the time. I can see how route finding would be a nightmare in a white out in winter. We were lucky we had a beautiful day.
Did the road walk to the summit and back. Touch of wind with great views. Companion trip report has details and photos.