Hi, I'm really not familuar with this... but I believe that the IR port on a mac has different frequency levels than what your audio/video appliences does. I believe that you actually have to buy a piece of hardware (which should come with software) to do what you want. I believe there are USB devices for this....
but as I said, this is only off the top of my head. If anyone can prove me wrong, I would be delighted to hear of this. I too have a laptop with an IR port...