Connecting to Arduino

I have made an SLI style dash using an Arduino board and a TM1638 Led module. It works perfectly in iRacing (Example videos below)

My issue is pretty fundamental. How do I connect my Arduino to rFactor2? Just so I can begin trying to make my dash work over here too. Cheers.

 

A few methods are possible. I didnt do a lot of work, but managed to get something going with "
"

Code:

....
int baudRate;
gcroot<String^> portName;
gcroot<SerialPort^> arduino;

...
arduino = gcnew SerialPort(portName, baudRate);
arduino->Write(Convert::ToString(......something.......));

Was a long time ago, and my C has since rusted!