From wherever you are ordering, find out what their normal shipping time is (for argument's sake, let's say 5-7 business days). About 10-14 days from your arrival date (enough time to allow for the order to be processed, shipped and delivered in advance of your arrival), place your order and use your name as the receiver and the name of the resort & their address as the shipping address. If possible, put your reservation number for your hotel next to your name. If there is an area on the order in the shipping section for special instructions, add in something like "please hold for guest arriving on August __, 2012". Then when you check in, ask if they are holding a parcel for you.
Most of the Disney resorts are pretty good, from what I have read, about accepting and holding packages for guests who have not yet checked in. If you are thinking of sending the package to your park and fly hotel and want to be sure they are okay with it, just call them to see if they will accept a package on your behalf.
We have done this multiple times and its awesome!!! Saves us a ton on shipping (as often an order of a certain size will quality for free shipping within the USA), and helps circumvent the issue of companies who won't deliver to Canada.