Here is an example for creating converters for your own class:
function doTest() {
var p = AJAXDemo.Examples.Classes.Demo.GetPerson().value; // synchronous call to the server-side method
// access the properties of the Person object here
alert(p.FirstName);
// Now, we want to save it, we call the save method of the instance
// and get a boolean if succeded.
var b = p.save();
}