I updated your scripts to work with the 12.04 official release.
I tweaked a bunch of things to reduce dependencies, output a bit more info and made it a bit more stable.
tweaks to use full release 12.04, and curl
improve build.sh to check md5hash of iso
more improvements to build.sh, remove some external dependencies
add a bit more output on progress
add a bit more info to README
add docs/usage to README
added MIT license