You have to rent your tux before your cruise - you cannot book it on board.
This is the info I got from HAL's website under
PLANNING & ADVICE
Clothing & Dress Code
Formalwear for ladies and gentlemen can be pre-ordered for your use during your cruise by calling Cruiseline Formalwear at 800-551-5091 or make your reservations online
. Your formalwear will be in your stateroom when you board. Cruiseline Formalwear Packages
I believe that any alterations that need to be done can be made on board by the tailor.
Hope this helps. Enjoy your cruise.