You can list by calling the regular Res line - any agent can do it as it's as easy as listing a fellow NW or Mesaba/Pinicle employee. As mrs747er said, you WILL need a paper ticket issued by Delta before actually flying, but it's pretty straight forward. I haven't listed anyone in first that I recall - but I have seen people listed for First - granted, if this week was any indication, the flights are pretty full - I had a bit of a time getting from SEA to NYC and home this week - got lucky, but I was surprised!