I think shorting is possible in Hong Kong stocks - subject to an uptick rule. It's quite complex, but in essence it means you can't hit a bid, but have to leave an offer and wait for a buyer to lift it. There are markets (Greece) where there's no potential to go short, but CFDs are still offered. The only prerequisite is really decent settlement procedures.
Not sure who offers HK at the moment - think Cantor's used to, but it's not on their website at the moment. Anyone who has offices in the Pacific region is probably a fair bet.
Nick