The hardest part has been compression. The icons used to have a file size limit of 1.94k (2000 bytes), making an animated icon under those specs can be a challenge. Although more recently, I believe nopoles upped the icon file size to 4 or 6k.
look through for a icon creator and you stick in you own 50x50 images (up to four) and create it... to get it on newschoolers you gotta right clcik on it and save it somewhere