oh great idea!
try 407-363-6200, merchandise hotline, press 1 to speak to a live person. They could do a purchase over the phone and see if it can be arranged through the resort delivery program with a special note on the package so that when the gift shop person at the Polynesian gets your package they will know to get it to your room. Send me a PM if you have trouble once you try, I used to be a merchandise and PPU / Resort Delivery, so I may be able to be of assistance.