Multilanguage service

Hi,

What I want to accomplish is a multilanguage web service, where language is determined by first two characters after base_url. That is, when user enters "example.com/en/someController/someMethod" it will fire up the someMethod in someController, but before doing that, it will set a global (actually defined in My_Controller) variable to 'en'.

I know I can handle this by using routes, and passing the language code as first parameter to methods, but this requires a lof of work, plus, we have a lot of existing code, and modifying it would be a nightmare.

So I thougt, that maybe using hooks is the way to go? There is a "pre_controller" hook, Is this possible to get an uri segment and then call a controller/method or maybe rather to alter routes dynamically from there?