It could work well as a 4-5-1, similar to the set up we had against Arsenal in the CL semi finals last season, although this time it would involve Nani being the central striker with Valencia and Park playing on either side of him.
This would allow Valencia and Park to focus more on attacking, which they are both quite good at, and as Nani has one of the most powerful finishes in the team, and he is quite fast, he could be a possibility to start upfront against CSKA. If this doesn't pay off, then Owen and Rooney could be brought on as subs, and the traditional 4-4-2 could be reverted to.
Who knows?? Maybe it would not work out, but it could also be a permanent change if he played well as a striker. To be honest, i think it's worth a try.