Simple: Use the [tab] key to help you nevigate.
Example: When booted up you are at ~/ . The afterinstall directory is at / .
To access it, just type "cd .. [tab]"
Then the first forward slash will appear.
Now you have "../" , then type aft [tab], then the prompt will complete your typing and returns "../afterinstall". Then you can change into this directory.
The scripts are not that buggy, imho. I also use them and they work quite well.
That is the reason for making a new rootfs tarball. You don't need those scripts anymore.