I used the Rob Mills chocolate cake mix and used flax seed instead of eggs. Just follow the directions on the bag, it will tell you how to use the flax seed as an egg replacer.
For the icing...
Earth Balance margarine that is soy free
Double the amount of icing sugar and food colouring
EG. 1 cup of Earth balance with 2 cups of icing sugar (it's fluffy)
* Use a mixer/blender to mix the margarine with the icing sugar.