Yeah Ive never heard of email transfer before either. It must be a local Canadian thing.
I think the best way to transfer is to do what is usually called a TT (Telegraphic Transfer). You may be able to do it online, or you may have to phone your bank.
You can have your canadian bank exchange CAD-HKD first and then transfer HKD to your HSBC account. But in the past, I have found that the exchange rates are better in HK. So in other words, you should open a CAD multimoney account with HSBC HK and then transfer CAD from Canada to HK. Do not allow the Canadian bank to do the exchange. They usually want to do it, but inform them that you only want to send CAD. Then once the money is in your HSBC account, you can use HSBC online to transfer from CAD to HKD.