Trigger Input Manager 'Fire1' with Oculus Touch controller button

I'm fairly new to VR and I'd like to know what the best practise is for detecting button inputs from the Oculus Touch controllers. I'm detecting the controllers' rotation using:
InputTracking.GetLocalRotation(XRNode.LeftHand);
...and that's working well, but I'm at a loss at how to detect a button press from the Oculus Touch controllers.
I've read a few things online about an Oculus 'plugin' OVRInput, but do I really need to download a plugin to detect button input in Unity? I'd prefer to take advantage of the in-built Unity Input Manager, if possible.

I'm doing a check for Input.GetButtonDown("Fire1") but I think that value in the Input Manager is assigned to the left mouse. How would I assign that to a Touch button?

What do people here generally do? What's the best/normal practise?
Thanks for any pointers (or especially examples!).

EDIT: OK, I've realised my 'Fire1' code was working, just not with the button I was intending. But I'd still like to know how I can assign Touch controller buttons to actions in my game... Thanks!