The most current is the VR package, which you can get through the package manager, or from here: https://github.com/worldmaking/vr
These can talk to the Oculus and SteamVR runtimes, but I'm not sure if this will work on mac. In theory the latest build has mac support for SteamVR (and you can use Oculus with that), but I haven't had a chance to test it.
Otherwise, I also have a much older external for the oculus rift developer kit versions which did run on mac, which is here: https://github.com/grrrwaaa/max_oculus
Not sure if these will work with the consumer Rift, and you'd have to find the 0.4.4 Oculus runtime, which I'm not sure if it will work either.
The current crop of VR headsets require pretty high-end GPUs and there's not a lot of macs that have that capability, so the majority of VR work has been focused on Windows.
I'm having a problem loading the [vr] external; Max is giving me 'Error 126 loading external vr.' Do you have any ideas on troubleshooting? I've posted details here: