From Hong Kong University, "Preference for admission is given to local candidates but, in exceptional circumstances, a few overseas applicants may be selected. All applicants, both local and overseas, are expected to have a good working knowledge of English and Cantonese."
From the Chinese University of Hong Kong, "For the remaining 26 programmes offered by the University, including Medicine Programme, Chinese Medicine and Chinese Language and Literature, applicants with working knowledge in Chinese are preferred." But they don't comment on the international candidates chances of gaining admission.