Lars - you can always contact the promoters through the festival website (www.wacken.com). There are links in there that can take you to the appropriate band application area. There are definitely some quality Intromental acts that I'm sure would be welcome at the fest - also, the recent North American expansion partnership with Glenn from ProgPower is a nice move that will only help the label grow in stature. Go for it!
The organizers of this year's Wacken Open Air festival — which is taking place August 2-4 in Wacken, Germany — are streaming select performances and press conferences from the event live (and some pre-recorded) via the festival's official web site ... http://www.wacken.com/en/woa2007/main-bands/woa-livestream/