I did this the last two times we went down (2006,2008). I was able to ship the box home from the resort. I printed my name and address onto a piece of paper and I packed the last of the roll of packing tape, the label and a magic marker (for crossing out any markings on the package from the trip down). When I was ready to ship, I packed the box up, taped it up, taped the label on it and brought it down to the concierge desk. They weighed it, asked how I wanted to ship it - I said UPS. Then they asked how I wanted to pay for it and it was that simple. Since I shipped it the day before we left I was able to charge it to my room. I did this from AKL and POR.
I sent down most of my luggage and snacks, coffee/filters, toothpaste, sunblock, etc for two of us. Then I just carried on a very small bag onto the plane. The cost to ship was only about $16.00 each way at the time. Not much more than the luggage fee the airline charges.
I forgot to add that the UPS website will allow you to calculate how far in advance you need to ship your package according to how much you want to spend. I had to ship about 7 business days in advance to get the cheapest rates. Also ship either UPS or FedEx. USPS does not deliver to the resorts, only the other two do.