Comment 86 for bug 1166442

Sure thing Imran! I'll tell you the way I did it which may not be the best way but it works:

Grab the 3.9.6 kernel source in .tar.bz2 format from kernel.org.
Extract somewhere in your user directory.
Go into the /drivers/input/mouse folder and open elantech.c

Since I have no idea about applying patches, I just removed the lines specified in the patch file and added the ones specified.
To be safe I attached a modified elantech.c you can just replace the old one with. If this isn't OK someone please tell me and I'll remove it btw. All credit goes to kendatsuba of course for the changes.

Now...
1) run "make oldconfig" and press enter to any questions, which will select the kernel defaults for any new options added between your previous kernel and this one.
2) "make -j`cat /proc/cpuinfo | grep -c processor`" -this will run make on a number of processes equal to threads your processor has. This can take a while, on an i7-3636QM (8 threads) this took about 10 minutes.
3) make modules_install
4) make install]

And reboot into the new kernel.