tofu

you can have the account opening forms sent to a hsbc branch. then you fill the forms in front of the personal banker and the personal banker courier the forms back to a hsbc branch in hk to complete the process.  
they used to do it to their "known" clients, but not sure are they still doing it.
even open an account in hk now, they need proof of address.

tofu

proof of hk address is for proofing you are hk resident.  you live in hk.