it should be a relatively simple download-and-overwrite operation.
In all my years as a professional game developer I have learned a few things. One nugget amongst them is that these things are never simple and almost never without serious risks. I myself have had my harddisk wiped (yes deleted from the root level) by one of these that was coded just a bit too nonchalantly. ;-)
(Not that Alex would ever code anything like that I hasten to add) ;-)