Edit:
IMPORTANT: Check the pinned v5 thread
I finally managed to get loading skins functionality working

Therefore, as of now, MXM Skinner is a "proper" skinning app
Supports:
Drawing skins (WYSIWYG)
Generating skin XML's
Loading skins
Perfect for the new skinner
Edit: I am going away for a few days, so I will not be replying to any questions until Sunday. Still, feel free to leave comments/suggestions/bug reports, which I will check when I get back.
Edit: I'm back and fixed the "component (file) not found" bug in version 3.1
Edit:
*Download removed. Check out V5 in the pinned thread.