I make a cap so to speak for the hair using lofted nurbs curves, then insert lots of isoprams, withthem all still selected I then make curves form that, then assign the hair to the curves. Works a treat.

The advantage is that you can then just hid the curves and use the history of them, so to adjust the hair you can just adjust the nurbs cap.

Oh and when your animation just hide the hair system and the curves, then swich on for render time