How can I access ViewState in a class other than a code-behind file?

For both Session State and Application State, we can access the values stored there from a class other than a code-behind file by using the Current property of the HttpContext class. For example:
•      HttpContext.Current.Application["HitCount"];
•      HttpContext.Current.Session["Email"].ToString();
If we were in the code-behind file, we could access these by simply using
•      Application["HitCount"]
•      Session["Email"].ToString()
For View State, how can we access values stored in View State when we are in a class other than a code-behind file?

I experimented a bit, and verified a method in a class located in the App_Code folder would not recognize Session or Application unless I preceded it with HttpContext.Current. Further, it did not recognize ViewState at all. Further, I found that "static" methods in any class (including the code-behind) would fit this scenario where the HttpConext.Current would need to precede the Session and Application in order to be recognized, and the ViewState is not recognized at all (at least not by the Intellisence of Visual Studio 2008). How can I get ViewState from the page to be recognized in these methods/classes?