If you do an archive search on "HoKeY" or "HoKeY lottery" you will find plenty of information on the topic. Just be prepared for the expletives.

SunLover

PS - fare codes H,K,and Y qualify on CO for a potential chance at an international cash + dollars upgrade (if the non-rev's don't beat you to it). It might be worth checking out partner airlines such as NW or DL.