My middle girl (3) has a developmental delay that began with the speech problems. She has been in a program for 7 months now and has improved a ton. She will be going into a mixed class (half special needs, half "normal" kids) next year.
But potty stuff! She had the same problem, no interest in it at all. We've been "encouraging" (strongly) since she was two and she just didn't want to. Finally this week, with them finished school and no plans to leave the house, I decided she was going to learn.
Day 1, I put her on the potty as soon as she woke up. She threw her usual fit over it but we sat there for about 20 minutes and read potty books. Nothing. Ah well, gave her a skittle, set an alarm for 30 minutes and tried again. This time there was a little bit of pee. Made a huge deal about how awesome it was, gave her a sticker on her potty chart and a lollipop. Set the alarm again for 30 minutes. All day we set the alarm, and sat on the toilet every 30 minutes. No pee, she got a skittle; when she peed, she got a lollipop. By noon she realized that if she peed every ten minutes she got a ton of lollipops (they are tiny ones). Whatever, at least she is going. It went great though, she was going. Lots of wet panties but not a big deal.
Day two we nixed the alarm and I just helped remind her. We toned down the candy (none when she didn't go anymore) and I let her lead it a bit more. She started to figure it out, less accidents and a poop as well! She was actually upset about the diaper at night and woke up two hours after she went to bed to go to the bathroom.
Day 3, even better. Barely reminded her and only had two accidents. Less candy again, only a lollipop every other potty trip.
Today is day 4 and the first day I felt brave enough to leave the house with her (only for about 40 minutes). No accidents yet, haven't needed to remind her (although I'm paying attention just in case she leaves it too long).
So yes, this is a kid that I have been struggling with potty training for two years and have talked to her doctor about several times. I was starting to think she'd be in diapers until she was 10 because she is so damn stubborn. So my advice for those with kids with developmental problems and no interest in doing it - wait until you know for sure they are 100% capable of it and then just make them do it. Don't leave your house for several days and focus A TON of energy on it. Eat lots of candy (or whatever it is that does it for them), wash lots of laundry and sit in the bathroom a lot.
edit: Also this:
http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1. I just installed this in the kids bathroom and it is super handy. She didn't like potty chairs and it was annoying to constantly be moving the little toilet seat one.