Well if you google the Hotel Milano, you will find a map on their website. The hotel is not far from the cruise terminal. (Of course it may depend on which cruise line you are sailing on (but I assume Carnival since you posted in the Carnival area) Judging from the map you are within a few blocks of the terminal. You may still want a taxi to haul your luggage unless you are traveling really lightly. The cruise ships dock in the Old San Juan area for reference.
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, Celebrity Silhouette 2013