I bought an icing kit (piping set) and it came with a recipe for Royal Icing, but it is really different to others. I just wrote the method roughly. This is it:

Royal Icing

1 lb Confectioners sugar
1 Tbsp lemon juice
1/3 cup water
Food colouring (optional)

Put sugar, lemon juice and water in bowl. Let sit then whisk till smooth.
Add food colour until desired colour is achieved.

Makes 1 3/4 cups.

Would this work? All the recipes online call for egg whites or meringue powder.
*EDIT*
Just found the link to the recipe on the website of the company:

http://kuhnrikon.com/recipes/recipe.php3?id=181