I'm using ltools, but if I can't make a custom installer, I'd be willing to use any of the softmod installers.
I definatly think it can be done, but it would be a lot easier to just change the boot dash to xbmc. I can do it in less than a minute minus the time it takes for the FTP transfer of XBMC.
Yes, I know, but sometimes I do softmodding at a friend's house who does not have FTP access. It's much easier to just have XBMC autoinstall with the savegame instead of having to bring the Xbox back to my house to get the softmod setup finalized.