Hmm, that's a tough one. I'm surprised it's not on iTunes. Square Enix is usually pretty good about releasing their stuff via that avenue. One thing I will say is that the blu-ray version DOES give you the option of saving an MP3 and a lossless version to a USB drive and getting it on your PC that way.
Other than that, unfortunately, I don't see any other means to score it. Square hasn't being using CDs lately because (presumably) it's cheaper to press one blu-ray than four to six CDs and the packaging that goes with it. Doesn't help folks with CD players (read: everyone else), but for now it seems to be their thing.
If I hear anything useful I'll be sure to let you know.