problem adding an item to a builtin array

I have a problem when I try to do something like this

var enemies = new myClassName[0];

in the inspector works great, but if i want to add a new object to the builtin array directly from my .js code how i can do that? i tried this:

var enemies = new myClassName[0];

enemies.Push(new myClassName()); -> error enemies.Add(new myClassName()); -> error enemies= new myClassName(); -> error enemies *= new myClassName() -> i is the last index + 1 (error)* *enemies.Resize=N; -> error : 'self.punto.Resize' has not been correctly processed.

* *

(and sorry for my english i speak spanish)

//this shows up in inspector
var builtinArray : MyClass[];

function Start () {
  // this creates a js array with the contents of builtinArray
  var enemies = new Array(builtinArray);
  enemies.push(new MyClass());