I've been looking at this unit...shown from ebay for info purposes only;
http://cgi.ebay.com/ChannelPlus-Mode...QQcmdZViewItem
It takes four inputs and can frequency synthesize your choice of four output channels within it's range. This unit is fine by itself if you want to cable all your sets individually. To add it to your existing cable, you need their insertion box which adds the output to a cable pass-through signal. It has four DA outputs I think. Search more for this info.
You might be able to use a splitter in reverse combining the incoming cable and Channelplus output on the output sides of a splitter and the input side then going to your main cable house wiring without the four output pass-through DA box. This would depend on signal strength needed around your house.
Using their insertion box, you would then assign your DVD, nannycam, laserdisc, etc. to unused channels on your cable feed. They have a variety of boxes for one or more channels. Obviously, the feed would have to hit a cable-ready device like a orphan VHS for a tuner and then on Ch 3 or 4 to your vintage set. In my case, cable channels 2 and 5 are open and would not need a tuner.
Anyone else ever try these boxes?
Dave A