DSS designed to be installed with and without prepared CD. So, You can download ISO from <url> and run it</url> - Still not - or install DSD on the top of your ready-to-use debian stable system.
with CD:. Still not ready
Without CD. To the ready debian stable system: Still not ready
user@host:~$ wget http://dss-project.org/dsd/pool/main/b/base-files/base-files_7.2+blackeye1_amd64.deb
user@host:~$ sudo dpkg -i base-files_7.2+blackeye1_amd64.deb
user@host:~$ sudo apt-get update
user@host:~$ sudo apt-get install deep-space-debian
DSD public GPG key located here: http://dss-project.org/dsd/conf/deep-space-debian.key