Ubuntu Hardy
Install the package libotr2 using your favourite package manager. For example:
sudo aptitude install libotr2
Now get the python-otr package (i386/gpg, amd64/gpg) and install it.
Debian testing, Ubuntu Intrepid (or newer)
Install the libotr2 and the python-otr package using your favourite package manager. For example:
sudo aptitude install libotr2 python-otr
Archlinux
Install the libotr package:
pacman -S libotr
Get and extract the python-otr package from AUR. Afterwards, build and install it:
# assumed that you downloaded the file to /tmp/python-otr.tar.gz cd /tmp tar xfz python-otr.tar.gz cd python-otr makepkg -s pacman -U ../python-otr-0.2.1-*.tar.gz
Distro-independent source and binary packages
You can find source and binary packages for libotr at their website.
At the python-otr page you can find distro-independent source and binary packages. Consult your distro manual, google or whoever on how to install them.