Well, try to type
Code:
mount -o remount, rw /system/
in terminal emulator. And try to use your script again.
As i said, i cannot have permanent R/W system... but, thanx to this command line, i've also use crossix mod for swap internal/external SD ('cause finally it arrived from amazon!) and it work perfectly! So now im a very happy A100/ICS user!
So, if someone have the same problem of mine (rooted, but with no permanent R/W /system), just type that command line in a terminal emulator (before remember to use "su" command to be super user), and than do all the changes needed.
Form me, i use chmod 775 and cp commands to rename, move and replace crossix build.prop/sd swap files, but also fro remove some bloatware from Acer.
I home my experience can be usefull for someone else