You simply have to
- Download the .zip file below
- Exit Rainmeter
- Extract the contents of the .zip into the Languages\ folder in the root of your Rainmeter installation.
By default, this will be C:\Program Files\Rainmeter\Languages\
- Restart Rainmeter
This is for Rainmeter 4.0 ONLY. Do not use this .zip file if you are running any earlier (3.3.2) or later (4.1) version of Rainmeter.
Version dated: January 8, 2016
- Spanish Modern
Version dated: January 10, 2016