Flash in TWRP after making a backup.
Please read all info below.
!!! CAUTION !!!
Use at your own risk. Backup before flashing.
I am not responsible for bricked devices,
thermonuclear war or your monkey dancing samba!
The installer changes one file. It overwrites \system\etc\permissions\handheld_core_hardware.xml
with an updated version to enable the Google Daydream support.
There is also the remover ZIP. It restores the stock OOS 5.1.3 permission file.
After flashing - get ready
You wiped your cache and dalvik and boot the device.
Go to your application list and show system apps.
Delete cache and data of the Play Store app so Daydream is
downloadable via Play Store. Open Play Store,
do not forget to set your previous Play Store configuration and install:
• Daydream Keyboard
• Google VR Services
Some reported that setting to skip all intros in Daydream developers options
fixed problems that occured.
Start, set the other config which is needed and try. For me it works fine.
The only thing that is a bit sad is that the 5T with full HD gives a not very sharp display view - it is grainy.