I would like to introduce a little bash script called ro-chroot.
you can download it here: http://vectorlinux.osuosl.org/Uelsk8s/ro-chroot
It was made to help developers in packaging,but it has many more uses.
It uses aufs to overlay your / and keeps track of all changes done while its running.
What this means is that you can download files delete files change files and exit the script and all your data is safely untouched, but all of the changes are neatly stored in a CHROOT-RW dir.
how to use it?
download it: wget http://vectorlinux.osuosl.org/Uelsk8s/ro-chroot
change its permission to executable: chmod +x ro-chroot
run it as root: ./ro-chroot
make any changes, create a package.
exit by typing: exit
Any questions,post them below