Such an old OCX control should not be used anymore.
You may use the Windows API
Communication Functions[
^] to implement serial communication yourself.
Because serial communication is often not a simple task, have also a look on articles and classes providing a simpler interface. Use the Search function here at CodeProject to find one that matches your requirements:
mfc c++ serial port[
^].
Even if you did not find what you want, the sources may be helpful to understand serial communication.