[Octane]

Напиши setter (для IE6,7 событие onpropertychange)

var obj = {a: {b: "c"}}, el = document.createElement("div");
el.__defineSetter__("a", function (arg) {
	obj.a.b = arg;
});

alert(obj.a.b);
el.a = "d";
alert(obj.a.b);