Robin from the Howard Stern Show follows that exactly...and it definitly has worked for her! First she went on a 40 day cleanse (I think), dropped a bunch of weight, and now incorporates the lemonade mixture into her every day life.
If I remember correctly, she has it for breakfast, has a good sized healthy lunch, and then has it for the rest of the day. That way you don't have to worry about eating too late, and most of the calories you consume for lunch will be burned off throughout the rest of your day. I think it's a great plan to follow, after you have done the Master-Cleanse for it's full effects. Because you still keep up your metabolism and can enjoy food, but receive some of the benefits of a cleanse and diet in a healthy way.
That's what I'm going to do after my next 20 day cleanse starting on the July 7th (after my b-day) :) So let me know how it works for you and if you see any results!