If you are more adventurous...

You can open up the back of the TV, find the internal wires going to the TV speakers, cut them, and splice in your own wires leading out of the back of the TV, ending them in whatever connectors you need for your headphones. You might have to actually drill a hole in the back of the TV to get these out. I actually did this one time, but, you've got to have a bit of couraage!