Chris,
If you're looking at starting a new company:
The normal process would be to approach an accountant. They usually have a stock list of shelf companies which you can buy and transfer to your name. The process takes about 3 or 4 days to transfer the company and get the paperwork done. (Will cost around HK$1500-5000 depending on the type of company you want)
Once you have got the paper work and BR certificate you can approach a bank to open an account. Most banks (unless you have a good reference) will hold your account for a month while they run their independant checks with the company registrar to ensure that you are indeed the owner.
If you're looking at buying an existing company or shop then you really need to get a lawyer or accountant involved to approach the company anonymously and figure out how much the company is really worth, if it has bad debts, if it is profitable etc.
Anyways, this is fairly general advice. If you have specific questions, post them here. There are several people on the site who run and own small businesses and will be willing to share knowledge with you.