I agree with jane01, get him to bed earlier in the morning for a 1.5 hour sleep, then another 1.5 hour sleep afternoon (say around 1.30-2pm). I find this works for my 10mth.

Also do you use a dummy?

In Australia they have sleep schools that you and your LO attend for either a night or two. Loads of my friends have done this and they say they are invaluable. Do they happen in HK?