LG is usually one of the first ones on the 0999 list.
Assuming you have the V6 box:
Turn the TV on with its own remote control.
Press clear and TV, then press the thumbs down button 3 times and then OK to reset. Then press any button, the green light on the remote control will go green for about 10 seconds whilst it pairs with the V6 box.
Then, hold clear and TV again and key in 0999. Press the channel up button a couple of times and the TV will go off. You don't have to hold the button down, you can click it seperate times. Once the TV goes off, press ok to lock in the code.