UnityScript files get compiled to classes underneath just like C# files. You can access a static field the same way as C# class. For unity script the class name is the file name so it should be
Edit: Here is an example of how this works. ACSharpScript.cs goes in some folder I define to ensure it's compiled last:
...then, in Standard Assets I create a UnityScript file called AUnityScript.js :
the C# is incrementing the static COUNTER field in the UnityScript class and an instance of the UnityScript (the instance created when you hang it on the graph) is reading the static field every frame. Hang these on the scene and try it... you will see COUNTER incrementing every frame.