- 1 - Go to this website http://kernel.ubuntu.com/~kernel-ppa/mainline/ and you'll see a huge directory tree of kernels. Find the directory for the kernel you want/need and click on it.
- 2 - In each of these directories you're going to see "BUILD.LOG", "CHANGES", three items that begin with "linux-headers", two that begin with "linux-image" and one that begins with "linux-source". The "BUILD.LOG", "CHANGES", and "linux-source" are completely unimportant right now. We're only worried about "linux-headers" and "linux-image".
- 3 - Download and then install the following IN THIS ORDER: first get the linux-headers file that ends with "all.deb". Second get the linux-headers file that ends with "i386.deb" or "amd64.deb" depending upon what architecture you need. Finally get the linux-image file that ends with "i386.deb" or "amd64.deb" again depending upon what architecture you need. Honestly it doesn't really matter what order you download them in, but you need to make absolutely sure that you install them in this order.
- 4 - Reboot your computer and you're done.

Disclaimer: I do this all the time and it's yet to not work for me. You do need to understand that there is an inherent risk associated with all low level system stuff like this. If it borks your system, I claim no responsibility.