I don't "do OO" development in ColdFusion. I'm starting with that statement not to spark another debate about whether to use OO in ColdFusion, but rather to clarify that while this post is about a principle of object oriented development, you don't need to "Do OO" in order to learn, use, and benefit from composition.
In the last "OO Principles" entry, I talked about encapsulating CFCs. The example that I use was the need to have a datasource in a component. It should be clear from that entry that you could pass in more methods as well.