I’ve submitted some patches to make squashfs-tools work on Mac OS X 10.7+ and all major BSD flavours: https://github.com/plougher/squashfs-tools/pull/3 . They’re pretty non-invasive.

Phillip, if you could please let me know what you think. I’m certainly willing to make any reasonable changes.

And others, please test on your machines and let me know how it goes. Also, if there are other OSes or other versions of OSes you’re interested in, I can try to port to those as well.