So you want WordPressMU in a specific language? The process is pretty much the same as in single WordPress.
You’ll need a translation file in your specific language. Most of these have been created already and are on that page. Please feel free to add links to specific WPMU-based translation files in the comments for others to find.
I’m assuming here you already have WPMU up and running, and confirmed it works.
On the server, take the .mo file in your language and make a new directory under either wp-content or wp-includes. Either should work. Put the .mo file in this directory.
Now, edit your wp-config.php file. Look for
define (‘WPLANG’, ”);
Put in the name of your language file, WITHOUT the .mo. in my case, it look like this:
define (‘WPLANG’, ‘it_IT’);
because it was Italian. Save the config file. If you check the backend, you’ll see nothing has changed as yet. You’ll need to visit two menu items.
Go to Site Admin -> Options and scroll down right under where the site admins are listed. There will be a drop-down box for preferred language, and English will be selected. Pick your installed language.
(Note: this menu only shows if you’ve installed at least one language file.)
That sets up the default language for each newly created blog from this point. you may have noticed that the backend of the main blog’s admin area is still in English. Go to Settings -> General and there will be a Blog Language drop-down near the bottom. Select the language you like.
Now when you save, you should definitely see everything in the backend displaying in your language. there may be a few stray English words, especially in themes and plugins. We’ll go into localizing those in a future post (guest posts for this welcome).