Instancing

Hi guys. I am really impressed by the instancing demo with boxes in SharpDX. I could use it in my project but I need to be able to set color of every box face individually. Does anybody know how should I approach it ? I could do it in WPF version but it looks tricky in this method. As there is a single model that is multiplied it is hard to apply various colors on every face. Any suggestion will be greatly appreciated.