Ok, created a patch myself to get "
[ROM][LOLLIPOP][LB/UB][5.1.1] eXistenZ Premium | 3.1.0 " working on our ZL.
Though i can't get Remote Control working, so if anyone can do so, by all means.
I was already on 5.0.2, so best if you are already at 5.0.2 or higher.
Steps, flash the following in sequence in CWM :
1. Xperia Z eXistenZ Premium v3.0.0 (optional, you may want to remove the boot,img in the zip file), followed by v3.1.0
2.
Xperia_ZL_eXistenZ_patch_222.zip
3.
XZDR-removaltool.zip
4.
ZL-lockeddualrecovery2.8.22-RELEASE.flashable.zip
5. Reboot
Wait about 10 mins.
You should now be at 5.1.1, cheers