Yes, you use it on your scalp. It has enough cleaning agents in it to clean the scalp without stripping the hair.
No, you should not be greasy and "get used to it". Your hair should feel clean and light, but more moisturized and softer than with S&C.
Are you following the directions in the CO article?
ETA: CO Wash: http://forums.longhaircommunity.com/...e&articleid=18