Mixed in Key problem

So, I finally got around to running mixed in key on just about my whole music collection...the problem is that I didn't check check the rename files options before I analyzed all my music...

Is there anyway to write the key and bpm to the songs in my collection without re-analyzing the whole collection?

Also it has a warning about deleting information in ableton and traktor if I rewrite the song title...has anyone had experience with this? Should I just add the key tag to the comment?

Any help would be nice,
Thanks

http://www.mp3tag.de/en/ This should do it for you

^^^^^

But what if he's on a Mac?

mp3tag is only going to work on PC.