Two pictures in one icon

Does anyone know of a good tutorial (or have any tips) that deals with putting two pictures in one icon? I don't want to make a blend, but I just want to have two pictures in it. It should sort of be like the one that I'm posting with, although i don't think I did that very well so it's not the greatest example. The icon that I want to make would use two totally different pictures. Hopefully you know what I mean - anybody know of a good tutorial for something like this? Thanks very much.