https://launchpad.net/~anders-kaseorg/+archive/subversion-1.6

Edit the apt sources, using your favorite editor:

$ sudo emacs /etc/apt/sources.list

Add these lines to the end of the file:

deb http://ppa.launchpad.net/anders-kaseorg/subversion-1.6/ubuntu jaunty main
deb-src http://ppa.launchpad.net/anders-kaseorg/subversion-1.6/ubuntu jaunty main

The add the key signature:

$ sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 413576CB

where 413576CB is the Signing Key from the web page above… update the apt cache, and force a reinstall:

$ sudo apt-get update
$ sudo apt-get --reinstall install subversion