In this snowless winter being suffered by Eastern skiers I've found myself too often partially spinning and skidding on icy hard pack. At times I've felt like a disoriented top. Watching some of the other sliding bodies, I don't think I'm alone.
At such periods, it's good to go back to basics. Well-tuned skis, including properly sharpened edges, count for a lot. Another need with most of us, I think, is to correct too much upper body action. The idea is to quiet the upper body. but when it's icy, we're less sure of forming a platform with our skis. Then, the tendency to flail about with the arms "to make sure we get our skis across that fall line" can be overpowering.
The best advice, therefore, is to return to a solid stem christie. Concentrate on initiating the turn with a small stem of the uphill ski. Immediately apply pressure on the inside edge of the uphill (outside) ski. and keep hand and pole movements to a minimum.
Since keeping speed under control is of paramount interest here, we should complete the turn and immediately start a new one, stepping on the new outside ski. He/she who hesitates is a guaranteed skidder-spinner.
The quieter we get the upper body, the more we'll feel the knees and ankles doing their proper job of turning the skis. Eventually, they tell me, you should be able to transfer that feeling to parallel turns.