Step 1: Ingredients
As long as it's white or light colored, it should work wonderfully.
1/2 c. sugar
1 (8 oz.) pkg. cream cheese, softened (or your lite/fat free variety)
1 tbsp. lemon juice
1/2 tsp. vanilla
Dash of salt
1/4 c. milk
Food Coloring (I have gels)
6 zip style sandwich/snack bags. The snack size is a little easier to control when piping your mix out. You could alternatively layer the colors in a piping bag, and pipe directly into the center of the pan, so each color pushes the others out.
Mix everything: food wise, not literally everything, that could lead to problems; once you have a smooth almost pancake like batter you can move on.