Nexus 4 KitKat Download

1. Rename the package you've downloaded to "update.zip" (no quotes)
2. Place the update.zip package into the Android SDK/platform-tools folder on your computer (do not unzip it).
3. Power off your tablet
4. Hold down the volume up, volume down and power buttons when turning on your tablet.
5. Your tablet should startup into the fastboot menu, when you see that connect your Nexus tablet to your computer via USB.
6. Use the volume up/down keys to navigate to "Recovery mode", then press the power button to boot into recovery.
7. When the Android with the red exclamation point appears, press the power and volume up buttons at the same time. This should open the recovery menu. 
8. Use the volume up/down keys to select "apply update from ADB," then press power to select it.
9. On your computer, open up a command prompt or terminal window.
10. Using the command line, navigate to the Android SDK/platform-tools folder on your computer
11. On Windows, type: adb.exe sideload update.zip; on Mac, type: ./adb-mac sideload update.zip; on Linux, type: ./adb sideload update.zip
12. The update should begin installing; and when it's done, select "reboot system now" using the volume buttons, and power to select
13. That's that, you should now be running Android 4.4.

Note: we didn't have to toggle on ADB debugging for this to work, but if it doesn't work for you, maybe turning that option on will help. To do that, you need to first access the Development options by going to Settings > About and tapping the Build number 7 times. Then, go to Settings > Development options and enable USB debugging under the "Debugging" menu group.

Download: Android 4.3 (build JWR66Y) to Android 4.4 (KRT16S) & Android 4.4 (KRT16O) to Android 4.4 (KRT16S)