Yer right - the thread is gone. The one I found was the guy in Yokosuka. Not close enough to swing by, but that's what the Takkyubin is for, yeah? I'm wondering if he's not doing mods anymore. I've got a friend that modded his PS2 perfectly first shot, so I'm sure he could handle this. He said he'd rather not try my X-box, to avoid frying it, but he's likely better than me, although I'm willing to give it a shot.
What boards did you try? There was one shop that would mod GC's to play imports for 6000 yen, which I used once but they don't do Xbox's.

I'm thinking Akihabara's got to have someplace somewhere that will mod them, but finding it is the problem. There's a shop on the 4th floor on the main street (about 200 meters from the station) that has gamesharks, imports, and some other dodgy stuff. That's worth looking into - they could at least recommend someone I'd assume, but it's a bit far from my house.
I'm in Ikejiri - one stop from Shibuya, so not too far from you.
Maybe we can put our heads together and figure something out.
BTW - Tokyu Bunka Kaikan has an advanced showing of Matrix: Reloaded tonight if you're into that. First one starts at 09:30 - that's a week before the Roppongi Hills premiere, but of course, doesn't have the nice seats. I would'ev never known, but my better half told me last night.