engine.SetGlobalValue("TestViewModel", new ScriptResultConstructor(engine));
engine.ExecuteFile(@"c:testtest.js");
Console.WriteLine(engine.CallGlobalFunction("testViewModel"))

public class ScriptResultConstructor : ClrFunction
{
    public ScriptResultConstructor(ScriptEngine engine)
        : base(engine.Function.InstancePrototype, "TestViewModel",
            new ScriptResultInstance(engine.Object.InstancePrototype))
    {

    }
    [JSConstructorFunction]
    public ScriptResultInstance Construct()
    {
        return new ScriptResultInstance(InstancePrototype);
    }
}
public class ScriptResultInstance : ObjectInstance
{
    public bool Result { get; set; }
    public string Message { get; set; }

    public ScriptResultInstance(ObjectInstance prototype)
        : base(prototype)
    {
        PopulateFunctions();
    }

    public ScriptResultInstance(ObjectInstance prototype, bool result, string message)
        : base(prototype)
    {
        Result = result;
        Message = message;

    }
    [JSFunction(Name = "TestScriptResult")]
    public ScriptResultInstance TestScriptResult()
    {

        var model = new ScriptResultInstance(Engine.Object.InstancePrototype, true, "ok");
        return model;
    }



}

function testViewModel() {
    var str = new TestViewModel();
    return str.TestScriptResult().Message;
}