What I ended up doing was to pass a parameter to silverlight that contained System.Threading.Thread.CurrentThread.CurrentUICulture.ToString()
Then, I used the following bit to adjust the language to the incoming parameter
String
strLanguage = properties.Language;
LocalizationManager.Manager = new LocalizationManager();
LocalizationManager.Manager.Culture = new System.Globalization.CultureInfo(strLanguage);
LocalizationManager.Manager.ResourceManager = FileUploader.ResourceManager;
wham bam works like a charm.