Prepare Watermelon Lemonade. Using 2 cups of the Watermelon Lemonade, fill compartments of 2 ice-cube trays or 8x8x2-inch baking pan. Freeze for at least 4 hours or until firm. If using the baking pan, scrape frozen mixture or break into small pieces. In a blender or food processor, combine frozen Watermelon Lemonade, 1-1/4 cups vodka or gin and 1/3 cup melon liqueur. Cover; blend or process until smooth. Pour the mixture into chilled martini glasses. Garnish with a lemon twist. Makes 8 servings.