I've successfully added model attachments back into my 3D engine. I'm providing a video entry that gives some details about how I implemented it. Because all 3D engines are different, I only give show shader code, but I think the explanations are nice and clear. This is probably one of my most informative videos. If it gets a nice reception, maybe I'll make more. I really put a lot of effort in to this video. It's taken me a few days to complete. I actually wrote a script for it and planned how I'd put it together. Enjoy.
If you'd like information on creating a skeletal animation system, here are some links. In the Direct X SDK, there is a sample on this topic as well.
Here's a basic bone system that uses Open GL, but the concepts be used with Direct X
A wiki that explains what skeletal animation is.
An old discussion on Gamedev.net about implementing a bone animation system.
A basic Skeletal Animation Tutorial
Feel free to check out my Google plus page for updates and check out my YouTube channel.
Google+: Squared'D Game Google+ Page
YouTube: Squared'D Youtube Channel