This turns out to be somewhat more difficult than I realized. To me, this should be a simple procedure. Of course, it’s not so I’ve since found several links that help with just how to do this.
The first is the official Google/Android page which describes their solution for this:
Android Accessory Development Kit
The next is a special chip that takes all of the pain out of interfacing to the Android USB port:
FTDI Android
I’ve since ordered a couple of the chips and assorted hardware including solder paste to do some ‘toaster oven surface mount’ experiments.