OK - I have now fitted it as follows:
1. I have positioned it roughly the same as the pictures at the start of this thread but with the left hand side of the panel lining up with the the left hand side of the controller port nearest the middle.
2. I removed the front panel, and removed the small circuit board (CD eject and power on/off) as well.
2. Using hacksaw, Stanley knife and dremmel drill (with cutting disc) I cut out a rectangular shape to fit the dimensions of the front of the panell. A bit of judiscious filing and cutting a it fits the front panel OK.
3. I then had to remove the metal prongs on the front of the inside of the lid so that they didn't foul the LCD. I also had to cut back three plastic positioning lugs in the front roof of the lid.
4. I then cut out the metal panel (with grill holes) which is positioned in front of the disc and behind the LCD as it wasn't allowing the LCD to be corerectly positioned.
5. I also had to remove a small triangular shaped piece of plastic from the front of tha case which holds the front metal grill in place (front bottom corner).
6. I then put it all back again - including fitting the new pro switch (with buttons that light up).
7. Fired unit up and all is working except I can't read the LCD screen (even though it is enabled and glowing blue) - I shall start a separate thread on this.
Xecuter 3, the pro switch and XBMC are all working.