Basically as you would do a simple backup and restore of the data configuration, but there is a tool that comes with DIRT built in support for several languages including US English, French, German and Japanese. By default it will display the language the Windows operating system is set for. If that language is not supported it will default to US English.
To manually force the tool to show a different language than the default, you can select the Help | About menu option and click the Change Language hyperlink on the About box. The languages installed will be presented in a drop down list and the display will update into that language immediately when you select it.