With latest push, you can create an Iframe dynamically using document.createElement, and put it just about anywhere.
Kevin's immediate program fires immediately, though it is still not right in a way that you can't see.

As I've been doing cross-frame references, I come to realize an unexpected problem.
In side the frame f, create a script s, and then ask: s instanceof Script, and it fails.

Subtle ...

It fails because classes are created per window, that is, per frame.
If a script is instantiated by any means inside a frame f, it is an instance of f.contentWindow.Script, not an instance of Script.
I'm almost certain that these classes should be defined across all frames, across all windows, like Array and Date and the like.
It would also save time and memory, and that's a nice thing too.
I was going to do this a while ago, put them all in eb$master, but there was a snag, a reason not to, and I don't remember the gotcha right now.
I'll go back and look, because it's a tad more important than I thought it first was.

Karl Dahlke