As we have already mentioned, the working holiday visa is intended for cultural exchange ad does not allow you to work for one employer for more than 3 months.
Having said that, it is quite possible for a person on a working holiday to find an employer he/she would like to work full time for.
If this is the case, your next step would be to make an application for an entry employment visa (even though you will stay in Hong Kong on your working holiday visa while the application is processed). The application process takes 4-6 weeks. If you are granted the employment visa, you should then go to Macao and thus terminate your working holiday visa on exiting. You will then put your new employment visa on an empty page in your passport and you enter Hong Kong in a new capacity.
So how do you secure an employment visa? You will have to pass the approvability test – proving that you possess special skills, knowledge and experience not available in Hong Kong and this is why your employer is recruiting you.