Dunno, but I'd assume they use different sized chisels for fiddly bits, and then finish off the smoothness with sandpaper/similar.
Just found this:
Sometimes a monumental stone statue would be roughly shaped even while being quarried, like that of Osiris that still lies in the granite quarry where it originated, near Shellal south of Aswan. The finer work on a sculpture was done with chisel and mallet, the latter club-shaped during the Old Kingdom and subsequently either club-shaped or round-headed. This method made it easier to determine the force of a blow and, by adjusting the angle of the chisel, to alter the thickness of the flakes removed. To achieve a smooth finish the sculptor used an adze, familiar from our description of woodworking, followed by grinding and polishing with the oval stone or with silicate powder, leather and water.
Oh... just noticed you addressed that to Steve. Not trying to impersonate him.
:$EDITED: 11 Aug 2007 16:12 by BOUGHTONP