Being a chair is a socially awkward task. You can usually do this simply from the program page. Make sure you have the current title of their paper as well, since titles often change as well. Chairs rarely do this and it isn't expected, so it sure makes an impression when it occur s. The hardest and most important job is trying to keep panelists on time.
Most panelists run over their allotted time.
At least a month before the conference, send an email or letter to all the panelists reminding them of h ow much time they will be allotted. Then, remind all the panelists before the panel gets started of the time constraints. Also, announce to the audience during the introduction that you will be holding the panelists to a particular time constraint. Hand each panelist a slip of paper with time remaining at 5 minutes before the end and 2 minutes before the end. Do this with the discussant as well.