C# - Web Application Azure Settings?

We're currently refactoring our ASP.NET 4.0 Web Application to run on both plain old IIS and Azure. For the Settings (in the Properties namespace), I'd like to implement the State Pattern with an AzureSettingsState and a StandaloneSettingsState, which both provide settings getter methods.Now could anybody help me figuring out how ASP.NET deserializes the non-String values (e.g. TimeSpan or StringCollection), so that I can deserialize them on my own in the context class? All settings seem to be strings there.

public abstract class ConfigStateBase
{
public abstract string GetSettingValue(string setting);
}