Loading one AS3 swf into another - how to access properties?

I have an swf with a main document class and some public properties.

public class loaded extends MovieClip{
 public var x:String = 'readme';

Now, I load that in. If I do…

function onInitHandler(loadEvent:Event){

I get [object loaded]

But I can’t access any properties. If I try to read x, it gives me an error.

Does anyone know how I do this?