Hi,
Actually, it looks like the company wants all requests done via email....here it is.
xjttravel@expressjet.com
You can view the agreement on xjt.com....select the TRAVEL link, then bottom right side under personal travel select interline agreements, and then its a PDF for the SWA link.
However, if you live by a Branded station, they can service your request at the counter with no delay.
peace
brown