You've got to be kidding me, man.
I do use GIMP. Who hasn't? Yes, GIMP has a GIF/Animation display, but it obviously doesn't give you the proper x, y coordinates for Graal head, body alignment. Even the official head/body templates do not come with this info, because they exist only as separate entities. Aside from this, it takes a bit of effort in setting up an animation vs just popping the images in the Viewer.
The only method for a player to extract proper alignment, would be to demo Noob head + body in-game, take screenshots of every single frame that makes up a template (80+ basic frames, not including special actions/animations i.e. dances, guns), import all of it into a program, align the head and body templates to the screenshot, and finally GFX over the aligned frames. GIMP (or whatever graphics program you desire) is only an instrument, and has only a fraction of relevance to the heart of the subject.
Side note... why kids always use a winky face when they think they're being smart?