Well you would have to compile it or find a binary ISOzone seems to usually have the latest binary so you could search there as for running well its a app like any other so just FTP and run it now if you would like it as a your main dash than its a bit different but not by much
You can download just about every XBox homebrew item from; http://www.eurasia.nu including XBMC. As a general rule, always use the latest version of any piece of software, though check up on the forums at http://forums.xbox-scene.com/index.php?showforum=335 in case any current version of something you use has a bug, in which case use an earlier version. I have to say though, that as far as I know, no current XBox has any bugs that make it better to use earlier versions.