Payment of Application Fee (Urgent! Please Respond)

Hello, I'm a Vietnamese student who's currently living and studying in the US. I would like to visit HongKong for my upcoming springbreak and I'm in the process of document preparation to submit by mail. However, I noticed that the payment for the application has to be either cashier order or bank draft in Hong Kong Dollar. But in the US, most of the banks only do US dollars, not any other currency. Could you help me please? Is there an alternative?

If I apply for the visa in person at the Chinese Embassy, do I have to worry about this issue? Could I just pay directly there?