1. Downgrade to 4.2.2 (67 firmware) by flashing the ftf file of your region. Search the ZL thread to find your ROM on 67 fw.
2. Root the 67 firmware by bin4ry's method or cubeundcube method.
3. Make a TA backup using DevShaft's method. This is important for relocking your bootloader.
4. Upgrade to 101 using PCC or SUS. You will lose root. Make a ftf file of the update files that has been downloaded to your computer using flashtool.
5. Unlock bootloader from Sony. You will lose DRM.
6. Flash a custom kernel by Doomlord or Gustavo RD78. This is a modified stock kernel with cwm recovery built-in.
7. Now download the latest 1.94 update super su.zip from chainfire's website. Store it in your ext micro SD card. Flash it to root your phone from the cwm recovery.
8. To get back to stock recovery, use the ftf file created at step 4 above. Flash only the kernel and fotakernel from the ftf file.
9. Now relock your bootloader by flashing the ta backup you made at step 3. Now your phone is rooted with locked bootloader on 101 firmware.
I made a similar help thread for Sony Xperia Z here: http://forum.xda-developers.com/show....php?t=2656698
Go though the thread except using the custom kernel in that thread
. That kernel is Z specific. For the ZL use the advanced stock kernel by Doomlord or Gustavo RD78 in the dev section. Link for kernel for ZL is here:
Sent from one of my/our device/s