I've been working to make scripted enemies as simple as possible to set up, so that any competent quest maker can use them easily. Here's what I've got: http://www.youtube.com/watch?v=CXVD2gIfE7w
If you want to use them, you'll need at least RC2. Here are the files:
ghost.zh
AutoGhost enemies
Same files, different host
Look at AutoGhost.txt for the full setup instructions.
There are only a few enemies for now, but I'll add more, and I do hope I won't be the only one writing them.