so i found the answer.
// ResHelper
using CMS.GlobalHelper;
using CMS.SiteProvider;
// Get culture ID from query string
var uiCultureID = QueryHelper.GetInteger("UIcultureID", 0);
// Get requested culture
var ui = UICultureInfoProvider.GetSafeUICulture(uiCultureID);
var dui = UICultureInfoProvider.GetUICultureInfo(CultureHelper.DefaultUICulture);
var s = ResHelper.GetString("myculturevalue.test", dui.UICultureCode);
for those interested in the task, take a look here http://devnet.kentico.com/Blogs/Martin-Hejtmanek/June-2010/New-in-5-5-Provide-your-classes-from-App_Code.aspx
thanks