It’s basically a complete uninstall / reinstall with this route.
1) Open the existing version and close all editors and all perspectives
2) Exit Eclipse.
3) Run the Uninstaller that is located under the MyEclipse install
4) Run the 3.8.2 installer and point it to your existing Eclipse installation
5) Launch Eclipse and reopen any perspectives you need.
As an alternative, we’re going to provide an archived version of the update site very shortly. With that you’ll be able to download the site, expand it somewhere on your disk, then point Eclipse to it manually to perform the update.