If you can get internet access on your Xbox, but can't connect it to a PC for whatever reason, but still want the latest build of XBox Media Center, this is the guide for you.
1. XBFTP - Xbox FTP Client - Available in the usual place
2. Any app capable of un-rar'ing files. - I tryed using Avalaunch for this, but it just froze, perhaps because of the large-ish (35MB) file. The latest build (9-27-05) of XBMC worked though. (PM me if you know of another one that works.)
3. Any app with a file manager/boXplorer.
1. Initially, you will need a PC, but only once, to check for the address of the XBMC/XBMP xbins server. I would post it, but I don't know if that would be allowed. Just follow the steps you would normally take to get your xbins user/pass but look at the message it gives you about daily XBMC CVS builds. Get the address, user and password and fire up your xbox.
2. Launch Xbox FTP Client and enter the server info you just got. Assuming you got all the details right, it should connect fine. Go down to the build you want to download, and transfer it. (Note: When I did this, my Xbox froze after the download finished. The file was fine though.)
3. Now you need to launch whatever app you're going to un-rar with. I used XBMC and unfortuantely, it froze at about 80% done. Rebooting the Xbox, and just un-rar'ing the files it hadn't gotten to yet worked fine. (If you can't get the remaining files to un-rar, try un-rar'ing to different directory.) Un-rar the files to some directory, as long as it's not the current XBMC directory.
4. Edit the XboxMediaCenter.xml file, or, depending on the build, just use your old one. I use a script for XBMC called Notepad. As far as I know, the current version of Xpad will not open XML files. I know there's some other apps that can edit XML, but I can't recall them at the moment.
5. If you're in XBMC, exit out, either to a dash with a file manager, or to boXplorer or something similar. Delete your previous installation of XBMC, (leaving your scripts folder, and your XboxMediaCenter.xml if you want) then copy the new files to your XBMC directory.
6. Should be it. If worst comes to worst, and you can't get it to work, just wait until you can get FTP access.