Cheshire Figment says you can but all the posts I've seen him write about it are kind of complicated. You can't call the regular #, you have to call a special ticketing number. You may be required to mail your tickets back to Disney, or they may give you a special receipt # that you take to Will Call or Ticket Services or something. I would ask the question on the Theme Parks board (you can check the Ticket Sticky there but I don't think that is covered) and see what his current answer might be.
It's definitely not a standard or normal process, but it is possible apparently.