this is pretty difficult job to be doing (im currently resoldering a whole AV port to an xbox too), and its a pain in the ass.
i never found anywhere that was selling the av ports, so i had to rip one off an old dead 360. made this twice as hard, as you never gong to be able to get all of the solder off with the pins in the way , one pin is soldered to the grounding plate which will take alot of heat to remove. so the best bet is to remove as much solder as you can and start to pry the pins away from the motherboard, without bending them or pulling the pin out of the plastic socket
i havnt soldered it on yet so i cant give you tips for that. but i can tell you that creating your own by soldering wires is easier. just be aware that the top row of pin holes are smaller than the rest, 30 gauge wire will not fit through them so you will need something smaller