I did this one thanks to percysmith's insights. Asked similar questions and in the end the only route to achieving this was to use the CCB Dual Currency Card to pay the tax, and the HSBC Platinum to pay the CCB bill. Can't remember the whys and wherefores but it only works with this route.

In the end I'm not really sure it was worth it, as there is a redemption fee at the HSBC end, and in my case I didn't pick up a huge number of points/miles anyway. I've also received conflicting information about whether the HSBC Platinum Visa carries a fee or not. If it does, I wouldn't have taken the card in the first place. Guess I'm about to find out what happens.

What would be much better would be paying rent or mortgage and getting Asia Miles, but I've looked into this one extensively and it's generally not possible.