I was reading my brothers Xbox 360 magazine earlier and found this article explaining how to get Xbox Live Marketplace downloads from other areas.
Medium sized magazine scan - 1.4 Megabytes
Large sized magazine scan (If you can't read the small writing in the above scan) - 2.7 Megabytes
Make sure you download the file within 30 days, because that's when the files get automatically deleted. After that, you'll have to PM me for the scans.
I've been downloading Japanese trailers and there doesn't seem to be any problems with regional settings and whatnot. So no one needs to worry about that

.
Anyway, enjoy owning demos and trailers that may never make it to your country

.
Edit:
Oooooh, I forgot to say. If you make a Japanese account and you pick Tokyo as your prefecture, when you are registering the gamertag it will ask you to enter your city. When that happens, put in the following characters...
ときよ
Those are the characters for Tokyo, or more correctly To-Ki-yo.
If you feel like being awkward and end up choosing another prefecture, tell me what one and I'll rustle up the right characters for you.