Wojtek -
If you are using TestStand 3.0 or later the OIs built with the Operator Interace controls already support command line options. You can run the OIs with /? in the command line and you should be able to see the available options.
If you are using TestStand 2.x, you can customize the OIs to support command-line options and define what you need.
Scott Richardson (NI)
Scott Richardson
https://testeract.com