How do I add the mainline kernel PPA?

Note: test/debug kernel versions higher than your default kernel, e.g. 3.3, 3.4, 3.5, etc. are only provided via deb files, not via this PPA.

You probably want to add this PPA-- the only active one the kernel team maintains -- containing the latest pre-proposed kernel for each release:

ppa:kernel-ppa/pre-proposed

To my knowledge there is no way to add that to the /etc/apt/sources.list file There is a script that can get the job done https://github.com/GM-Script-Writer-62850/Ubuntu-Mainline-Kernel-Updater

Terminal Commands: (edit, more up to date info now in the readme at the above link)

cd /tmp
git clone git://github.com/GM-Script-Writer-62850/Ubuntu-Mainline-Kernel-Updater
bash Ubuntu-Mainline-Kernel-Updater/install

It will check for updates at login+60 seconds, you can check for updates at any time by running KernelUpdateChecker use -h or --help with that for help output

You can use Ukuu (which stands for ‘Ubuntu Kernel Update Utility’) This straightforward desktop app help you install a new kernel in Ubuntu, Linux Mint, and other Ubuntu-based distributions, using the “mainline” kernels published by Canonical.

Installation:

sudo add-apt-repository ppa:teejee2008/ppa
sudo apt-get update && sudo apt-get install ukuu

Then run "ukuu" from your appplication starter and it will show you all stable kernels to choose from. If you want unstable rc-kernels, you can disable the "hide unstable and RC Releases" flag in settings