Various fixes

Hi! I tried to run your tool on Ubuntu 12.10 and had several problems with it:

- Several paths were hardcoded
- cpio need root privileges (because device files are extracted)
- Some commands seem to be MacOS specific (but the Linux variant should work on MacOS, too)

Thanks in advance for pulling these changes.

Greetings, Michael

PS: This is my first ever pull request. If anything was done in a wrong way, please let me know.