lifegoeson

Rather than going to private school, I would suggest some public colleges such as the STEP program by Langara college,

http://www.langara.bc.ca/liberal-arts/step/index.html

lifegoeson

If you cousin plans to study for six months or less, I think your cousin can study as a "Short Term International Student" . Under this path your cousin does not have to be a Canadian or International student.  

Your cousin can study with a Temporary Resident Visa (i.e. a typical visitor visa). And if your cousin holds a valid HKSAR passport, there is no need to apply for this visitor visa.   

For admission detail on Short Term International student,
http://www.langara.bc.ca/liberal-arts/step/admission.html