From Airport to Kai Tak Cruise Terminal-If I take a bus, where to alight to connect there?

Hi

Pls advise where do I stop if I take a bus from the airport to the Kai Tak Cruise Terminal. Do I take Citybus A21 to Hung Hom Station and what bus to go there? Or do I take a bus to Kowloon Station and take another bus from there and what is the bus number? Which is the shorter route? Thank you.