First lets consider that you have updated your firmware and booted at least one time.
Now what we need is: one PC,cable to conect your phone to PC, and 2 tools: TWRP 126.96.36.199 for KK and Superuser or SuperSU at least 2.16, no less.
1. Connect your phone to your PC and install phone drivers correctly.
2. Copy superuser.zip or SuperSU on your SDCARD. Remember: only one is good. DO NOT FLASH BOTH. Flash the one you like.
3. Disconnect your phone from PC.
4. Extract files from TWRP 188.8.131.52 or the newest one TWRP 184.108.40.206 rev 2 archive on some folder on your PC.(Remember the folder )
5. In your folder that you extracted your archive you should find recovery.img and one scatter file.
6. Now you must have this FlashTool - SP_Flash_Tool_v3.1304.0.119 or SP_Flash_Tool_v5.1352.01. Not Optional.
7. Power Off your phone.
8. After power off your phone open FlahTool and browse for the scatter file your folder where are the recovery.img and scatter file.
9. Now comes the tricky part .
10. Load the scatter file and mark DA DL with check sum in SP Flash Tool v3. In SP Flash Tool v 5 dont need. They are allready selected. Recovery.img should appear checked.
10.1. I have updated the post with some custom scatter files for 4GB and 8GB Firmware. Iff you get diferent errors when you flash the recovery file use this custom scatter files.
11. Press Download NOT FIRMWARE UPGRADE.
12. Now, just now plug the cabble on your phone. Download should start and a green circle should appear.
13. After this you should have custom recovery TWRP installed.
14. Then boot directly to recovery your phone by pressing power with vol + and vol - butons together. Not Optional!
15. From TWRP flash Superuser.zip or SuperSU 2.xx. SuperSU is fixed. Works fine now.
16. Voila you have your KitKat rooted.
17. Now go to Magazin Play and download an RootChecker app and verify.
Hope this helped. For me worked with no mistake.
Waiting for feedback.
I have uploaded TWRP Corrected by Javum. Thanks Javum. And it is working on ROW 226 and 227 tested personaly by installing patches, superuser and making backups.
Sent from my Lenovo P780
SP Flash Tool_v.3 and v.5