From what I’ve seen, to allocate different materials to the same object you need to select the faces in edit mode, create a new material and click assign. So to have a different material on a part of shape you’d first select the whole shape, click new under the material pane and give it an overall colour/texture. The you would go in and select the faces you wanted to be different, click new again and select a different colour, then click assign.
I’m either doing it wrong or don’t understand
I’m using cycles in blender 2.63