Flyergold - The shuttle service that I linked to above does not require pre-booking. It has a counter inside HKG (Counter # 3D, in the "Exit B" area of the arrival hall). They are not that frequent, though, once every 30 minutes. The rates are in the link. HK$140 per person to HK Island, as I mentioned. Return trip to airport is HK$100.
The limos may not need pre-booking either. However, you may want to give them a call to make sure. Or you may have to wait at HKG for a while for the car to show up.
[This message has been edited by rkkwan (edited Feb 22, 2004).]