I checked the web site for Monroe Regional Airport (as Matt mentioned that he would drive anyone arriving by air to the venue), and unfortunately, it's basically useless for most of us, as it only seems to serve Dallas, Houston, and Atlanta. However, the Jackson, Mississippi airport, Medgar Wiley Evers, has flights to and from Denver International (according to Wikipedia), so if Joe wants to go this route, that'll save him two days of driving. He (and Clark, if he comes along for the ride) may be able to plan to meet up with Koltz in Jackson and travel to Monroe together (which is about 2 hours by car on Interstate 20).
Evers International doesn't seem to serve any other cities that have any confirmed ASC attendees living in or near them, unfortunately, so it looks like most of us are going to be putting rubber to asphalt.
No dice for Dave Smith, as neither the Monroe nor the Jackson airports serve Nashville, nor Chattanooga or Knoxville.

As for Duff and the European attendees, Dallas is probably the best bet, as DFW is the closest airport to Monroe that really serves any place far beyond the Southeast. It's still about a 5-hour drive from DFW to Monroe on I-20, though, but a flight from Dallas to Monroe is also possible, as mentioned above, although I'm not sure if such a short flight would be economical/practical (I've never flown commercially so I'm not sure what the costs/wait times would be like, nor do I keep track of each flight route's schedules-- Denver-Dallas and Dallas-Monroe, after all, may not be available on the same day).
I have yet to do any research on rail service between Monroe and other U.S. cities, but my guess is that there are few (if any) options there as well, because in America we just don't use trains for inter-city travel like the rest of the world does... at least not here in the South. I don't even think Gulfport has a functional Amtrak station anymore. You certainly never see ads for passenger rail services on American television (may be different in the Northeast, though).