Has anyone thought about getting Xfire support for Cortex Command?

I think you can rig it up yourself. No idea how though.

xfire_games.ini would be the way to go
Try and set up a new entry for CC, following the examples of the other ones. I don't think you could set up an icon for it, but hey, you'd have it recognizing the game, and that's a start... But only people with the addon could see it...
Also, post your xfire usernames so we can add each other