[B@rmaley.e><e]

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.3/jquery.min.js"></script>
<script src="http://james.padolsey.com/demos/plugins/jQuery/autoresize.jquery.js"></script>
<script>
$(document).ready(function(){
    $('#lalala').autoResize();
    // …
    // some moar actions …
    // …
    var rndStr = new Array(65).join('a').split('a').map(function(){return (Math.random() * 0xFFFFFF).toString(36)}).join('\n');
    $('#lalala').val(rndStr).trigger('change').trigger('keyup').trigger('keydown');
});
</script>

<textarea id="lalala">
ololo
</textarea>

Похоже, работает.