I'll let others who may know better answer the "lawful" aspects of how much. I have also been told I can bring back 5 Liters per person.
If you go to the message boards at http://www.vinow.com
and search for the thread "Bringing alcohol from USVI to states"
there are some good ideas on packing the liquor, etc. so it survives all of the handlers/portes etc.
The site and message board is a great resource for the USVI because it is 90% locals.
Phil & Liz