Hi Johnfitz,
Anyone can make use of the archives, but they do appreciate contact ahead of time, and yes, make an appointment. I suggest you visit the website:
http://www.utdallas.edu/library/coll...ac.htm#collect
If you go to that page, there is contact information at the bottom. If you're going in the next couple of weeks, I'd suggest contacting Thomas Allen or Paul Oelkrug, as Dr. Erik D. Carlson has just had heart surgery and is still recovering.
I would also suggest you make use of the website, and become as familiar with the Ferko collection (and the other WWI collections) BEFORE you visit, so you know what to ask for when you get there.
Greg