...Since then, Squeeze is no longer supported, so Debian moved the source repo's.
The original "/etc/apt/sources.list" file needs to be changed:
deb http://archive.debian.org/debian-archive/debian/ squeeze main contrib non-free
deb-src http://archive.debian.org/debian-archive/debian/ squeeze main contrib non-free
You can then install Squeeze packages: eg:
apt-get update
apt-get install debian-archive-keyring
apt-get install build-essential
Which gives you a basic GCC environment.
I applied the above on the original squeeze image, which may make it easier to get a working system, or, just make your own:
The original Debian image is also here:
http://files.wdlxtv.de/debian-squeeze.img.tgz