http://www.channel4.com/sport/football_italia/dec11i.html
The only way I can see Diego fitting in, would be if he was willing to fill in at LM when we don't have the ball.
We would also need to get a very good LB to get forward and maintain width on the left side when Diego goes into more central areas.
When in possession:
Buffon
Grygera-Legrottaglie-Chiellini---------
Camoranesi-Sissoko-Poulsen-Left Back
Diego
Trezeguet-Del Piero
When not in possession:
Buffon
Grygera-Legrottaglie-Chiellini-Left Back
Camoranesi-Sissoko-Poulsen-Diego
Del Piero
Trezeguet.
This is pretty much sticking to our beloved 4-4-2, it is just giving Diego the freedom to make it a 4-3-1-2 when we have possession.