From cake decorating class.
Cream shortening with electric mixer at low speed. Add powdered dream whip and flour; mix until well blended. Blend van-o-van and lemon and vanilla flavoring into the creamed mixture. Add 1/4 cup water and one pound 10x sugar and blend until moistened; then beat on #4 speed until icing is smooth. Scrape sides and bottom of mixing bowl often. Add the remainig water and sugar. Stir until moistened. Mix at #4 speed until icing is smooth and fluffy. Add additional water, a few drops at a time, if you desire a thinner spreading consistency. To stiffen, add more confectioners' sugar. keep icing covered with a damp cloth until you're ready to use it. Refrigerate leftover icing in an airtight container. Rewhip before using. NOTE: For chocolate frosting, add 3/4 cup cocoa.