Another option to look at is xvfb. It will create an X server for you to use. This is especially useful if you need to submit many jobs that can run on many different hosts.
Debian had a nice script to use around xvfb called xvfb-run. It will set your DISPLAY environment variable and then exec your program. I had previously gotten this to run on RHEL5 systems. You can download the files I was using at http://pages.cs.wisc.edu/~mick/download/xvfb-rhel5-x86_64.tar.gz
You would use it like so:
# Extract and start the virtual framebuffer X server
/bin/tar xzf xvfb-rhel5-x86_64.tar.gz
exec ./xvfb-rhel5-x86_64/xvfb-run --auto-servernum --server-args="-screen 0 640x480x24 -extension Composite" ./my-executable