You can use the standard 4.15 editor - they added the latest GoogleVR SDK to it and you are able to release Daydream compatible apps with it 
As for documentation these links are still valid for the Epic 4.15 standard editor:
https://developers.google.com/vr/unreal/daydream-in-unreal
&
https://developers.google.com/vr/unreal/arm-model
Edit: One thing not so well documented is you need to install android SDK 24 from the SDK manager manually as it is not installed by default when installing the android sdk packaged with the engine.
Hi,
I’m trying to get started with a project targeting Google Daydream. I’ve built from source from the GitHub branch for Daydream, and followed all the steps from here, but whenever I try to click the “Configure Now” button in the APKPackaging section under “Android” in project settings I get the “Could not overwrite project properties file” error.
I’ve gone through the forums to try and see if there’s any answers to this. It seems other folks have hit this same issue, but there’s not been any resolution (at least no usable answers posted) (e.g. here and here).
It sounds like some folks got this to work by just using the standard Unreal editor (not built from VS2015) but my understanding is I need this custom version for Daydream support. If this assumption is incorrect that would be awesome…
One proposed solution is to drop a blank properties file in that location, but if I do that I get a bunch of missing libraries errors.
Is there any up-to-date instructions for getting Google Daydream projects up and running in Unreal 4 that work? Been banging my head against this now for a few days.