[nickr]

I am thinking you would be better to copy the usr.sqsh file to another computer, unsquash it, make your changes and squash it again. Then copy it back and restart.

Although I am not entirely clear on a couple of things.

1. Whether you can copy over a mounted squashfs when copying the new usr.sqsh

2. whether there is any security mechanism that in the boot procedure that checks that the sqsh file matches a checksum.