1. Create a copy of the current translation that is located in: app/locale/en_US/IWD_OnepageCheckout.csv
2. Add a new folder to app/locale and copy file that is provided above
3. Edit file and update the second column with your translation
4. Note: the file must be edited using UTF-8 encoding (recommended to use Word)
5. To activate, go to Configuration -> General -> Locale Options -> Locale -> Set Up Specific Country
- If multiple stores are used then the specific store should be selected first