English Language Teachers Qualifications?? (Hong Kong)

Hello Everyone..
Is there anyone on this Forum who is teaching English in Schools, Colleges or Universities in Hong Kong?
I am a Mechanical Engineer and a Marketing Professional, but i love to teach English and Mathematics, I am currently learning a beginners Mandrin Chinese..But i heard everyone in Hong Kong speaks Cantonese..
Can someone guide me and tell me what course is good, which can give you a qualification certificate to teach English language in Hong Kong??
I am planning to do a CELTA and TEFL Course..
Which one is more demanding in Hong Kong?
Please let me know your views and opinions on the same..
Cheers..