Thanks, but I'm afraid that at least under linux, you have to have a Display set up even if it isn't used for displaying anything.
Wolfram support said they didn't know any way around it, but I was hoping someone did. We were trying to make this work with
a math kernel running under WebMath in such a way that could easily be ported to any machine, and setting up the Display stuff properly isn't easy because it is OS dependent.