Because you will have to authenticate with your amazon account, you can't simply specify the path to your storage area. You'll need to use a plugin of some sort.
Just because a plugin hasn't been updated in a while doesn't mean it's broken.
If you find a plugin to do what you want, I'd suggest giving it a try, even if it's been a year or so since it was last updated. However, I recommend setting up a testing environment, rather than using it on your live server.
A few possibilities:
Also, take a look at the tags for each plugin. They will likely lead to other possibilities.