I think they have broadcast most of the post-reunion concerts on WOWOW and this far no one has been able to really order it overseas (or if they have, they are not telling). I guess you need a) a Japanese billing address, b) a Japanese credit card/other means of payment (check/money order/etc), c) a Japanese ISP (Internet service provider) to watch over the Internet, d) a Japanese TV-service provider to watch from TV, or e) a combination of the above.
That still hasn't stopped some people from Japan streaming it online. The picture quality isn't the best, you might be kicked out every now and then and there is a limit of how many people are able to connect, but if there is something, I'm sure the links will pop up here and there, during the concerts.