How can I use DOMTokenList directly?

Question

The short of this is that I want HTMLElement.prototype.myList to function like HTMLElement.prototype.classList or .dataset

I can't figure out how to instantiate a DOMTokenList, however. I can get code to work against a polyfill (https://github.com/jwilsson/domtokenlist/blob/master/src/DOMTokenList.js), but not the native object. Against native, everything I try gives me: Uncaught TypeError: Illegal invocation

var n = new DOMTokenList();  // illegal
new DOMTokenList({}, 'foo'); // illegal

or via prototypes, I get more illegal / not function errors.

So does anyone know how to use the native code to do this?