The Child Development Centre on Victoria Peak (next to the Matilda Hosptial) is very good, it runs a pre-school, 3-6 years, about HKD 6000 for 5 mornings a week. They offer speech therapy and occupational therapy. I would suggest you start off there and then go to the Harbour School (Kennedy Town) or to the special needs class of ESF. I have been to the Harbour School for a look round, it's really great, a little expensive though (HKD112,000 per year).
www.cdchk.org(website)
info@cdchk.org(e-mail) tel: 2849 6138
www.theharbourschool.edu.hk
info@theharbourschool.edu.hk
Harbourt school tel: 2816 5222