I see. To do this, you should extract a little piece from the default embed code and include that in your page/script, which means you can put scripts and callbacks in place that will get picked up when the script gets loaded later:
window.twttr = window.twttr || { _e: [], ready: function (f) { t._e.push(f) } };
That puts the placeholder functions in place that widgets.js will pick up when it loads later.
Then, elsewhere in your code:
twttr.ready(function (t) {
// If you want to respond to widgets that initialize:
t.events.bind('loaded', function (elements) {
// then ..
});
// Or if you want to create a widget
t.widgets.createTweet('212', document.body)
.then(function () {
// etc
});
});
Let me know how you get on.
Ben