I have a cousin (now pushing 40, with a bachelors degree, a wife and three kids) who has cerebral palsy. He was the oldest child, and so when the next one came along, she potty trained by about age 2 and was walking and talking normally. By watching her, he figured things out better and got on the right track with all those things (he had tons of intervention and therapy as well). I know autism is completely different, but the same principle might apply.
I used the book Toilet Training in Less Than a Day with my second son when he was 27 months, after trying on and off for 6 months. It worked like a charm in less than a day. I only wish I had known about the book with my first son. The method was originally developed for toilet training retarded adults, but then was modified to use with small children. It's worth a shot; you can find it on amazon. I ran across another book on amazon called Toilet Training for Individuals with Autism or Other Developmental Issues. Good luck!