Try one of these:
http://www.griotsgarage.com/catalog.jsp?SKUupsell=94601
Theres versions without the compressed air.
And then if you store it often, you could consider one of these:
http://www.griotsgarage.com/catalog.jsp?&SKU=36740
Aside from the radio, there's no need to do anything but start the car and drive it around when it gets power back. If you don't have the radio code, it's off to the dealer with you.