Nearly manged to get this to work, using a single usb cable from the pi2 to the zero I powered and networked the zero as a usb ethernet device and it appears in the librelec network config settings.
I could then ssh into the zero from the libreelec pi2 and could access the internet from the zero but could not seem to make the zero appear on my network from machies other than the pi2.
The zero ended up on a different subnet and i couldn't fix the routing problem.
Looks like i'm going to need a wifi/ethernet usb dongle to network the zero after all.