It is pretty easy to organise yourself - just get flights to Hokkaido and let the Niseko based (Australian owned, staffed by expats) organise transfers, accomodation etc.
Thanks Topol - I vaguely remember somebody telling me that one of the villages in the Niseko area is not great to stay in (shaded most of the day and more exposed to wind). Have you heard anything like that?
Nula, I think the area you are referring to is outside of the main village near the Prince Hotel. However if you stay in the village, especially near the lifts, everything is much more convenient.