I think easiest would be bump up the deceleration. You can try, if default values for 8dir movement are
Max Speed - 200
Acceleration - 600
and Deceleration - 500, than just make it 2000, 5000 or what you'll feel is right.
edit-you're faster chrisbrobs <img src="smileys/smiley1.gif" border="0" align="middle" />