I guess you're close to a solution. It should be indeed a matter of effects.
You can check out the "Sprite effects.capx" in the c2\examples folder of your installation.
I'd say you would have to spawn a "mask" sprite over your icon, and move it accordingly to the part of the icon you want to display (if only the feet must appear, position the mask so it covers all the icon except the feet. Tweaking the Y position here should work)