having an extension and would like to add another TiVo box at the back of the house - can we buy and install the cable in preparation of an engineer coming out to install the box - would like the cable to be behind the walls etc and under the floor
This'll making a change from answering e-mail questions.
The answer is not really (but see a further comment below). VM's cable is a special type which is not commercially available. The cable and the connectors are designed to prevent the entry of RF noise into the cable network which can upset your connection and all other customers on the same circuits. The network includes the coax run from the entry point in your house to all connected devices, TV boxes and Superhubs, as well as the external street cabling. Doing what you want will also require a change to the cabling at the entry point to split it and work to re-balance the power levels on your circuit.
The better solution might be for you install ducting with pull cords and let VM provide the cabling and connections etc.
If you search this Forum you will find contrary advice and the name of an equivalent cable type/splitters which it is claimed you can use. Be warned that if you go down this route VM may refuse to install a second box. So you take the risk.
Superuser 2016/17 Use Kudos to say thanks Mark answer as "helpful" only when the problem is solved Please don't send me private messages unless I ask you to. I do not work for VM. The advice I give is based on my best understanding of VM policy and practice. You rely on it at your own risk.
I installed my own cable before Virgin Medias Engineer arrived you have to make sure you use a really high quality coax cable and some good quality F connectors. The Engineer was very impressed with my cabling as i had routed it to two locations and for both Tivo Boxes i have and also was told the power levels on the broadband were spot on. You have to watch the quality of the cable you use as if it is of poor quality it will affect the power levels on the modems in the Tivo boxes and your super-hub. Bad Power Levels = Slow Speeds, Drop outs and interruptions to service. to read more on power levels please follow this link to a page on these forums