I just transferred my China license to a ten year Hong Kong license with classification: "1-car, 3-motorcycle & 22-motor tricycle". cost: HK$900
Time: 3/4 mths - slow response from the ML license authorities to verify the validity of my China license.
Required: postal address in HK, a passport (or HK ID card) and a residential address if different from your HK postal address.

Once you get it, you can get the IDP for HK$80