If you want to make an auto-updater for your own software you can use the get object and the downloader object. Just have a page on your site that has latest version number. Use the get object to check it periodically, and if it doesn't match the current version use the downloader to download the newest version.
Not sure what you mean, but you could create an auto-extractor which simply overwrites the previous version. That sounds like auto update, but probably isn't what you meant to say.