No, the command line is actually set within the Steam menu. If you start up Steam, go to your Library, go to ARMA2 Operation Arrowhead, right click and go to the bottom Properties, then Set Launch Options you can alter the startup command line.
I think when you use the shortcut on the desktop, it launches the Steam app according to what is set in that Steam Launcher line.. As far as I know anyway..
Good luck!
BeachAV8R
