Defining Setter/Getter for an unparented local variable: impossible?

There's a few previous questions on StackOverflow questioning how one goes about accessing local variables via the scope chain, like if you wanted to reference a local variables using bracket notation and a string, you'd need something like __local__["varName"]. Thus far I haven't found even the hackiest method for accomplishing this, and haven't come up with a method after hours of exploiting every trick I know.

The purpose for it is to implement getters/setters on arbitrary unparented variables. Object.defineProperties or __defineGet/Setter__ require a context to be called on. For properties in the global or window contexts you can accomplish the goal of having a setter/getter for direct references to the object.

Object.defineProperty(this, "glob", {get: function(){return "direct access"})
console.log(glob); //"direct access"

Even in my tests with a custom extension I compiled into a modified Chromium that runs prior to any window creation where the context is the actual global context, and even trying to call this directly in the global context crashes my program, I can pull this off without a hitch:

Object.defineProperty(Object.prototype, "define", {
    value: function(name, descriptor){
        Object.defineProperty(this, name, descriptor);
    }
};
define("REALLYglobal", {get: function(){ return "above window context"; }});

And it is then available in all frames created later as a global routed through the specified getter/setter. The old __defineGet/Setter__ also works in that context without specifying what to call it on (doesn't work in Firefox though, the method above does).

So basically it's possible to define get/set guards for any variable on an object, including the window/global context with direct call to the object (you don't need window.propname, just propname). This is the is