No, to add -usetdm you right click on IS, select Configuration. Click the Game Configuration tab, select the Game from the first drop-down, and the Game Profile from the next drop-down. The field called Parameters needs to be -usetdm. If the Main Executable says TurbineLauncher.exe, you can also change it to TurbineInvoker.exe. I'm told that may work better when using -usetdm.