I don't think there is a ho ho bus. But there is public transportation buses. They cost a dollar a person ($2 if you are going far). If you walk out of the fenced port area and turn towards your left you will see a Wendy's restaurant.. in front of that there is a covered bench which is the bus stop. Ask someone waiting there if that bus route goes to Coki beach, they always seem friendly and are willing to help. We normally take the public bus to Red Hook to catch the ferry to St John. Its must less expensive than a taxi, as long as you don't mind the spartan conditions...
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007