...For the OP, why not just put $10000 into an HSBC smart vantage or whatever it's called (to avoid fees), get the $6000, and then close the account? The $10000 can be in any currency, for example a few of my friends brought £900 cash and didn't bother to exchange it.
Why all the effort if you don't need anything with the ATM account of Hang Seng. He probably wants the account available at a later stage without having to park money there for next to no interest.