Retro Rear Screens

[daeths]

I am going to install some rear screen headrest to keep the kiddy's amused on long trips. The type i will be getting are replacement headrests with the screen and DVD play built in. They power from a cigraette lighter but i want to run discreet wiring so they are live with the ignition.

The cables run through the centre of the two metal headrest supports and by removing the back of the front seats I can thread the cable inside the seat under the carpet.

My question is where is the best place to pick up the power so they work with the ignition on ??

Many thx