In System Center 2012, because the portal is based on SharePoint 2010, it is possible for the user to self-select the languages displayed subject to the SharePoint administrators configuration.
Here are the steps to enable this:
1) Install whatever language packs you desire for SharePoint. Download them here (SharePoint 2010 Server) or here (SharePoint 2010 Foundation). Then follow instructions here (SharePoint 2010 Server) or here (SharePoint 2010 Foundation) to install/deploy them.
2) Once you have the language packs deployed you can configure the language settings. As a SharePoint site admin go to the home page of the SCSM portal. Click Site Actions/Site Settings. You should see a new option for ‘Language Settings’. Click that.
3) In the language settings you can select the additional languages you want to enable for this site and then click OK.
4) Now each individual user can choose the language they want to display the portal in:
Note: I don’t have all my service catalog content configured for Russian, that’s why some of the content is displayed in English.
The default portal language will always be English, but userscan still change the language to whatever language they want so long as the administrator has enabled it on the site.