Let me choose the channels it goes to when not recording

Of the 6 tuners it has, it often idles on channels I never watch, and frequently 4 tuners will be on the same one. I would love to be able to set it to idle on channels I've selected in advance (for exaMPLE cnn), so when I turn the tv on it will be on channels I've chosen, and if the program it's on is interesting I can rewind to watch it. Wouldn't hurt to have the rewind extended to 1 hour instead of 30 minutes either.
Thanks.

Larry