I have cruised twice with Carnival, and both times wrapped up two bottles in my checked suitcase in bubble wrap, and never had a problem. I would make sure it was plasitic bottles, or bubble wrap it so you don't have a big fat mess if one of the bottles break. They really throw the luggage around. I would never put it in my carry on though, I have seen a couple people get their booze confiscated.
May i make another suggestion? Buy it at your port of departure and pack it into your checked baggage, the airlines really throw your luggage around, and with the weight restrictions, you have to be careful. If you buy it before you board the cruise, packed in your checked baggage you will have no problems and less change of breakage
The little two OZ plastic bottles available at the liquer store are great . I took 25 of these on a trip to Tahiti with no problem but that was before 9/11 and they did'nt look too closely . They are handy to have on shore excursions and other times .