Add field to Ticket Details Page
I am looking to add a field that will make the admin state the time allowed for a particular ticket to be resolved which is kinda like what you want to do only in reverse only that I will need to calculate variable times for different tickets before making them overdue.
I found an interesting thread to look at on that same issue and that might shed some light on yours and my situation.
http://osticket.com/forums/showthread.php?t=873(http://osticket.com/forums/showthread.php?t=873)