deluded Wrote:Can xbmc not just bash some new values into the video hardware registers to enable different video modes?Not without restarting the xbe (Xbox executable) or loading a other xbe, and the Xbox can only run one executable/process at a time. You can read this topic thread and this other topic thread for more detailed explainations and some solution ideas and workaround suggestions. The XBMC source code is also of course a good source of information.
Maybe you could 'just' create a small xbe program with a matching .cfg file (or xml) which only quickly preforms video-mode switching on the EEPROM in RAM before launching a specific xbe, ...so kind of like how Team-XBMC's shortcut tool (source code available in the SVN) works but with the addition of on-the-fly video-mode switching. That way you could use that xbe to launch XBMC each time, and maybe even add an option to edit that cfg (or xml) file from XBMC settings in the GUI. (The source code from nkpatcher and/or cherry's videomode code could possible be of help, more information here)