In case anyone is wondering, the Hong Kong Securities Market only accepts limit orders during the continuous trading phase (that is, 10-1230 and 230-4), this is unlike many other markets in the world that have a "market" option.
Some brokers, trading systems, implement a fake market price option, but as already mentioned in this thread, it can result in slightly unpredictable outcomes.
Just use a limit price and modify it now and then, for a highly liquid stock such as HSBC you won't have any problem getting in. And besides, you're looking to make ~30% and not ~1% profit right? So a difference of a few cents means almost nothing in the long term.