there is no custom application when working with IBSharp. Its a mature library, it works, and it provides strong typing and socket communication, exactly what the OP asked for.
Quote from vicirek:
I do not see myself saying that ActiveX is .Net or C++/CLI library.
However it can be used in .Net forms applications in any of the offered languages like C++/CLI, C# or VB with minimal effort.
In fact you can have rudimentary running test application using ActiveX in .Net within 5-15 minutes which would be considered out of the box.
Obviously there are other important considerations and choice of technology to send strings using sockets between TWS and custom application is up to the user.