Oculus said that Gear VR controller will work with existing apps as duplicate of the Touch panel on the HMD. Meaning touch and swipes on the controller’s touchpad should work out of the box.
Unfortunately it’s not the case for UE4 
Touch is reported as MotionController Face button 6, swipes don’t work (report same button 6). So basically touchpad on the controller works as d-pad, and only as d-pad.
The layout on the touch/d-pad is as following:
Touch - MotionController facebutton6
Up - MotionController facebutton1
Right - MotionController facebutton2
Down - MotionController facebutton3
Left - MotionController facebutton4
Press - MotionController Thumbstick
When I press any of the directions, 3 input actions fire simultaneously. For example pressing Up fires MotionController facebutton6, MotionController facebutton1 and MotionController Thumbstick all at once.
I think having a BP node that allows switching from touch interface to d-pad would be nice, along with not firing d-pad press with direction at the same time.
I will also report this to Oculus, so we all on the same page.