WARNING! This isn't working yet! (For me at least)
1. Add ppa source for pulseaudio-module-jack to Synaptic
> Settings > Repositories > Other Software > +Add :
ppa:motin/until-jack-is-included-in-main
2. Search for pulseaudio-module-jack and mark it for install. The version is something with +withjack0.
A whole list of packages have to be removed. Synaptic history shows:
Downgraded the following packages:
libpulse0
Removed the following packages:
gnome-applets, gnome-control-center, gnome-media, gnome-panel, gnome-session, gnome-settings-daemon, indicator-applet, indicator, messages, libcanberra-pulse, libpulse-browse0, libpulse-mainloop-glib0, padevchooser, paman, paprefs, pavucontrol, pavumeter, pulseaudio, pulseaudio-esound-compat, pulseaudio-module-bluetooth, pulseaudio-module-gconf, pulseaudio-module-udev, pulseaudio-module-x11, pulseaudio-module-zeroconf, pulseaudio-utils, ubuntustudio-desktop
3. Synaptic > Package > Force version ... on pulseaudio and pulseaudio-module-udev packages to the version with +withjack0 appended to their name.
4. Mark pulseaudio-module-jack for install again and hit apply.
5. Do some more Force version... on the +withjack0 packages to install, unmark everything that is marked for removal against my will
6. Mark pulseaudio-module-jack for install again and hit apply again et voila, it's installed.
7. Time to see if it works... save this page, close firefox-with-youtube, run and start qjackctl (Jack control), start
firefox-with-youtube again and see if the pulseaudio plug appears in qjackctl ...
Closing firefox was the showstopper, probably caused by too many essential packages removed in step 2.
It broke my window manager so I had to reinstall ubuntustudio-desktop to be able to log in again.
I managed to do this with Ctrl+Alt+F1, log in and enter sudo apt-get install ubuntustudio-desktop. After APT doing its job, removing pulseaudio-module-jack included, I could switch to the graphical environment with Ctrl+Alt+F7.
Retry another way, by building the files from source...