Tip #1 Get a guest assistance card

Disney wants to help families with special needs. One of the best ways they do this is with the "guest assistance card". This card is available at the Guest Relations Desk. You do not need a doctor's note or any a documentation but will be asked what your special needs are and what assistance you might need.

here's a great FAQ with more info:

http://pixiedustinn.com/disabilitiesfaq/GACFAQ.html