Here is a quick walkthrough of installing SID.
the wiring to the XBOX controller from the USB socket is easy as they are both the same colour!
All you need to do is cut the plug off an old controller and cut an old USB extension cable in half.
insert the SDcard or thumbdrive with SID on it.
Boot the XBOX with NO DVD inserted.
Select memory card
go down to required item.
copy over both SID and install to HD.
(use the right arrow).
Insert and boot Splinter Cell keeping the USB drive installed.
select “start game”
select “checkpoints”
Hopefully at this point XBMC will boot.
Select “backup and restore”
Backup EEPROM
Create MS Backup
Install Softmod HD
once this is done it will ask to reboot. Select this and remove the USB drive
BOOT
select “settings”
select “apperance”
select “PM3.HD”
you may also need to adjust the monitor settings as well.
