It's a lot easier with a main drain. Otherwise, you'll have to have a separate pump just for the task.

You *ALSO* need air-tight valve on the skimmer line; otherwise, when you try to drain the pool, you'll suck air out of the skimmer, and lose prime. Individual ball valves on the MD and skimmer lines would be good -- but one caution: ball valves trap water in BOTH the closed and the full open position. To winterize them, you have to put the handles on a 45 degree angle.