I did this about 2 years ago, part of the process is
- Knowing who you are, which country you're a citizen of and where you're resident for tax purposes and physically resident.
In my case it was simple - HK Permanent ID and local address + Indian passport.
With the Indian passport they asked for my tax ID (PAN), which I do not have as I have not lived or paid taxes in India for the last 30+ years. This caused a bit of a fuss, but it was accepted as I have a HK Permanent ID and my tax location was established as HK.
If you don't have a permanent ID your acct opening might be slightly complicated.
Like jrkob said - get on the online chat or even better, log into your account and send them an internal message and explain your situation, request that someone tell you what is required.
Even better, if you're in HK setup an appointment at a branch or the main office (takes a few days as they sometimes have a lot of people in the queue).
One more thing that caused problems for me / mrs was that signatures did not match on the US tax or datafeed agreement forms. Our forms were rejected 3 times when submitted at a branch. We ended up opening a new account and signed / opened the account with the same signature and it was all accepted at the main office.