public Task<TResult> FromAsync<TArg1, TArg2, TArg3>( 
    Func<TArg1, TArg2, TArg3, AsyncCallback, 
        object, IAsyncResult> beginMethod, 
    Func<IAsyncResult, TResult> endMethod, 
    TArg1 arg1, TArg2 arg2, TArg3 arg3, 
    object state);

TestClient proxy = new TestClient();
proxy.BeginInvokeOperation(Guid.NewGuid().ToString(), AsyncInvokeOperationEnd, proxy);
Console.WriteLine("Client:  Operation Invoked");
Console.ReadLine();

private static void AsyncInvokeOperationEnd(IAsyncResult iAsyncResult)
{
  TestClient proxy = (TestClient)iAsyncResult.AsyncState;
  string StrResult = proxy.EndInvokeOperation(iAsyncResult);
  Console.WriteLine(StrResult);
  Console.ReadLine();
}

Task task = ...FromAsync...

try
{
  task.Result;
}
catch
{

}

private static string AsyncInvokeOperationEnd(IAsyncResult iAsyncResult)

и

private static Task AsyncInvokeOperationEnd(IAsyncResult iAsyncResult)

и 

Task task = Task.Factory.FromAsync<string>(proxy.BeginInvokeOperation, AsyncInvokeOperationEnd, Guid.NewGuid().ToString(), proxy);