xtc--simple. I have 4 TV's running on 1 STB. Run coax out of the Voom STB to a splitter. Mine is a 1 in, 3 out splitter. Then run coax to whatever location your secondary TV is in. That's it.
The remote extender from Radio shack has a transmitter and a receiver. The transmitter piece is plugged into the wall, and is aimed at your STB. The receiver unit is located near your second TV, and plugged into a wall outlet. When watching the secondary TV, point your Voom remote at the receiver unit, and it sends commands to the transmitter unit, and that relays the commands to the STB. All you have to do is remember to carry the remote around with you.
I have my main system controlled by a Harmony remote, so I use the Voom remote for all the other TV's. The radio shack stuff consists of 1 transmitter, and 3 little receiver units (1 for each of the additional TV's). Keep in mind that any signal OUT from the Voom STB through coax is going to be converted to 480P, so if you have an HDTV as a secondary TV, it will be limited to 480P. Works great on an SD television.