Mozdzierz,
Open a Visual COBOL command prompt.
Create your text file containing
set printer_redirection=true
From the command line
set COBCONFIG=<path>\cobconfig.cfg
Run your app. If your USB printer is your default printer and your COBOL code is using ASSIGN TO PRINTER in the file descriptor it should now write to the USB printer.
To do the same from the Visual Studio IDE, open the Properties for your application, go to the Application page, click on the Environment button and set COBCONFIG to the value <path>\cobconfig.cfg. Then when you run your application from within Visual Studio it should pick up the configuration.
I hope that helps,
Gael