The update site location has changed since I mentioned it in my original post on May.
The new update site is http://download.eclipse.org/technology/babel/update-site/R0.10.1/helios.
The same is true of the exact name of the feature to install, which is now Babel Language Pack for eclipse in Chinese (Simplified) (93.78%) 3.6.0.v20121120125106 (I guess a few additional translations have been added).
For anyone referencing this in the future, if the url changes again (as it probably will), look for the updated URL in http://www.eclipse.org/babel/downloads.php.
For best results, use the Firefox browser..