Found this on crutchfield's website. It will allow you to use your steering wheel controls with a head unit.
http://www.crutchfield.com/S-yhQchQ0CU81/cgi-bin/ProdGroup.asp?g=118900&avf=Y
http://www.crutchfield.com/S-yhQchQ0CU81/cgi-bin/ProdGroup.asp?g=118900&avf=Y