You're going to have to convert that S-video to composite video.
here's a simple female/female plug to convert it.
http://www.cablestogo.com/product.as...=102&sku=13043
I don't know how good it works and it'll probably hurt the video quality some but that's the best I can come up with.
Also, Optical audio cables probably don't come with the advanced xbox cables so make sure you check before you leave the store..