Well I have a little bit of a lead, but it's not much. I recently noticed that some of the old soundtrack for this game was featured in a YouTube video by Channel Awesome entitled "Batman v Superman - Nostalgia Critic" at around the 1:53 mark. It looks like Channel Awesome and the game developers might have gotten their music from the same source. Maybe searching through the channel awesome community might prove useful, but things still look bleak.
Channel Awesome forums: http://channelawesome.com/forums/threads/music-from-video-batman-vs-superman-please.57553/