This plugin is experimental, although it does minimally work.  To make it
usable on Ubuntu Touch you need to disable PolicyKit authentication:

  $ sudo cat /etc/polkit-1/localauthority/50-local.d/10-click.pkla
  [Click Experimentation]
  Identity=unix-user:phablet
  Action=org.freedesktop.packagekit.*
  ResultAny=yes
  ResultInactive=yes
  ResultActive=yes

Obviously this is not ideal; we should be able to come up with a
finer-grained way to instruct the system that normal users can install Click
packages.

Once that's done, install packagekit and packagekit-plugin-click, and you
should be able to do things like:

  $ pkcon -p install-local foo.click

I have not done any work on figuring out how to make this work on systems
with aptdaemon.  If you want to try this on a normal Ubuntu desktop system,
then for the time being I recommend creating an LXC container for the
purpose:

  $ sudo lxc-create -t ubuntu -n saucy-click -- -r saucy -a amd64 -b $USER
