Superfish: drop down slide down / slide up effect - how to?

Superfish: drop down slide down / slide up effect - how to?

Hello,
I have just discovered superfish - it is awesome - the jquery
interaction is great.
Is it possible to have the superfish drop down items slide down and
slide up like the menu on this page?
http://spicebrains.com/multi-level-drop-down-menu/#examples
I really love that effect and have seen it on a number of sites before
and always thought it looked cool.
My current menu seems to show and hide the drop down items and uses
the following code.
$
'ul.sf-menu'
.superfish
{
delay: 1000,
animation: {opacity:'show',height:'show'},
speed: 100,
autoArrows: true,
dropShadows: true
            }
;
Thanks in advance.