as simple as it can get...
-download the file
https://android.clients.google.com/updates/signed-kila-ota-115247-prereq.TC4-RC19+RC28.zip
-put it on your sd card
-rename is to "update"
-turn your phone off
-hold the "home" button and while still holding it press teh power button to turn the phone on
-when the phone start you should see this screen
-open the keyboard
-press Alt+L
-pless Alt+S
-When it says "Installation Complete" you can press "Home" + "Back" to reboot.
-Wait for your phone to completely reboot and allow it to finish writing your radio rom during reboot, it may reboot multiple times.
-Enjoy