OK, that's exactly what I needed to know. With just a quick glance at those resources, it looks like Artisanix has knocked it out of the park in terms of his resources being user friendly. I'll need to pick it apart this evening when I get home, but it looks like the frames are all made with one mesh and each individual "canvas" is another texture all by itself. So this should make it so easy to create additional artwork for the frames in GIMP. I believe that there will be no real skill required other than scaling and cropping your screen shots. It looks like he even made normals for everything too!
As for the CK, it sounds like you should have no problem working in it. But here's what we will be doing in the CK:
CK Techniques
- Working within the meshes and textures directories
- Creating new Static assets
- Creating new texture sets*
- Applying texture sets to your new static assets
* Texture sets are not necessary if you set each of your meshes to point to your textures via Nifscope. However, since you want to do a bunch of these, I think the texture set technique might be better than using the Nifscope procedure. Plus, it's one less program to have to work with.

You'll need the DDS plugin installed in GIMP however:
GIMP DDS plugin - http://registry.gimp.org/node/70
More to come later.