Turning Off Cable Box via Software

I have finally gotten my HTPC set up working with an HVR 1600 (yay). However, when I want to record something, I need to leave my cable box on the entire night. I noticed in my IR blaster configuraton a setting for turning the box on before changing the channel, but it won't let me enable this (I get a message saying it isn't supported).

I am wondering if there is a way through software to turn my cable box on before a recording, then off immediately following. I amusing BeyondTV and a Hauppauge HVR-1600 with IR blaster. If it isn't possible with this software, does anyone know software that will make it possible? Thanks.