I do know that's possible using QlikView Server (Enterprise Management Console, System, Setup, QlikView Servers, Performance tab). There is an option passed on to the command "cmd.exe" in Windows (Vista and 7, not in XP and previous versions, likely 2003 Server and above as well)
that may help you, although since this is an operating system feature, I'd take this with care. This discussion may be helpful too. Make sure your operating system supports this.