Don't the admins generally create tickets for someone else in the? I would rather them enter the info of the person who called in for help instead of their own. Your requirements could be different.
I am guessing you could add a sql query to the db and grab the info., Take a look at include/staff/newticket.inc.php for starters.
Also take a look at this thread: http://osticket.com/forums/showthread.php?t=1105(http://osticket.com/forums/showthread.php?t=1105)