How to run wires through backrest / remove front seat upholstery

Hi, I would like to install a headrest DVD player and would like to run the wires through the backrest of the front seat.

I have some tools to pull the wires but I can't seem to find a point where the wires can exit at the bottom of the seat.

Does anyone know how to do this?

If I could just partly remove the upholstery at the back of the seat (bottom) I am sure I will find a small gap to run the wires through.

Hope my query makes sense and somebody can help. I searched the forum but could not find any clear pointers or instructions,

Thanks!