you can't ease dragging but you could fake it by using a
mouse handler (or hitTest) to initiate a loop that would ease the
movement of the movieclip.
i'm not sure the results would be satisfactory though
because, i believe, most users would be aggrevated to see a delayed
movement of the movieclip after (what they thought would be) the
start drag. and there must be some delay in movement initiation or
there won't be any perceptible easing.