It seems this much will be tougher than first anticipated because of the injuries.
A win is still possible, so we should go for it rather than settle for a draw.
With our current injury-crisis in defence, I would go with Zebina-Legrotagglie in the center. Sure it looks risky, but they're the only 2 players that actually play in the center of defence at the moment, and I believe they'll do well. Zebina can do well under pressure (Remember the Roma match 2 seasons ago at the Olimpico), and Legro should be fresh enough to perform well.
In midfield, I think it would be risky to use our usual flat 4 midfield given our situation in defence. I'd go for 3 defensive midfielders: Zanetti, Paro, and Marchisio with Del Piero in front of them as a play maker.
Here's how I think our formation should look like:
---------------------Buffon---------------------
Balza------Zebina----------Legro----Chiellini
---------Paro------Zanetti-----Marchisio------
--------------------Del Piero--------------------
--------------Zalayeta----Bojinov--------------
Camo for Paro/Marchisio and Palladino for Zalayetya or Bojinov in the 2nd half.
We should be able to win this game, but we'll probably concede a goal at least in the process.