With doors, the main issues are that the door is solid core, and that there be no leaks around or underneath it. I've used door seals from Zero International with good success:
http://www.zerointernational.com
If you're lucky Rod Gervais will show up and offer his substantial expertise. In the mean time, I never hesitate to suggest Rod's book which addresses this stuff in detail:
http://www.amazon.com/gp/product/1598630342/002-5726990-8501645?n=283155
--Ethan
