There is an inline hockey league for both kids and adults. The kids division U10 plays on Monday nights at 5:30 PM and 6:30 PM at Kings Park Centenary Centre (KPCC) near the Jordan MTR station. They still need some more kids to join.
I have attached some further information, the registration form, draft dates. They will accept applications for a few more days. They also have a Facebook page: Hong Kong Inline Hockey. There are a number of options to get inline equipment here in Hong Kong in time for the start of the league. Feel free to PM if you have other questions.