Internationalization in VAP styles

Hi there,

I'm trying to implement some VAP styles like header, footer, breadcrumb that handle internationalization based on a query parameter. This way, if the query parameter is lang_code and is equal to say "it" then it should show things in italian. Now, I've uploaded the language bundles into the styles as is the norm but I don't know how to dynamically set the locale for the site so that the appropriate language bundle is used.
What I had done before is used something like I18nUtils.setUserLocale(user, locale) but since this is a public site, the current user is null so I'm not able to do this. Is there an api to set the current site locale to a specific locale?

Thanks so much.