DoFo, there's nothing wrong with being optimistic but people who have lived here for a while are saying you probably won't get a job in IT with your experience... you should take it on board.
I think you're underestimating how low starting salaries are in this industry, what is required to make you irreplaceable by a local, and how important it probably is to speak Chinese (assuming you don't?).
Unless you have a really special skill, for example a co. is using a new piece of complex software integral to their processes and you happen to be an expert in it (much more specific than mac or admin skills) it will be hard for you to get a job especially since you need to be sponsored for a visa.
If moving to HK is the priority then, as I said, teaching might be your best bet.
Edit: but assuming you can get a working holiday visa, just do that for a while. Chances are after few months you'll be longing to go back home anyway!
HK is good for an experience but unless there are decent financial incentives, the majority of people* end up going back home. I don't think IT is the industry which will offer you these financial incentives.
*not everyone, before the 2 guys who hate their home countries and love HK start arguing