Bear in mind I have never owned an AppleTV, but won't it just sync back to your Mac? Or is it one way sync only?
If it does happen to be one way only, then surely there is a ripping tool you can use. A few years ago, I had some weird software corruption on my Mac and lost the majority of my iTunes library. But, since at that time I had all of my music on my 40GB iPod, I was able to use a free utility I got from versiontracker to move it from the iPod to my Mac, and all was happy again. Versiontracker is dead now, but MacUpdate is still a good source for freeware/sharware.