Finally, I got #OMEMO on the desktop!
For #Debian 8 (jessie):
> sudo add-apt-repository 'deb http://ftp.debian.org/debian jessie-backports main'
> sudo apt update
> sudo apt -t jessie-backports install gajim gajim-omemo
> sudo apt install python-potr python-openssl kwalletcli aspell-de libgtkspell0
Still buggy but functional. 🙂
Source: Privacy Handbuch (German)