How to use Visual Studio in a different international language

Visual Studio has always allowed to select the language of the environment in the Options window, Environment > International Settings section:

But, how do you get a new international language installed? The answer depends on the Visual Studio version:

Finally, there is a way to programmatically launch Visual Studio in the desired language:

devenv.exe /LCID <LocaleID>

where <LocaleID> can be 1033 for English, 3082 for Spanish, etc.