SharedOblect.send() with FMS3 and AS3.0

Now that AS3.0 client side script is more strongly typed, it appears you cannot dynamically add a callback function as in the following example. I've tried using a Responder in the client code and it didn't work. The code compiled and ren but the callback wasn't invoked.

// Sever side...
var myShared = SharedObject.get("foo", true);
myShared.send("doSomething", "this is a test");

// Client side
connection = new NetConnection();
connection.connect("rtmp://www.macromedia.com/someApp");
var x = SharedObject.getRemote("foo", connection.uri, true);
x.connect(connection);
x.doSomething = function(str) {
// Process the str object.
};