Currently - from memory - the wires both up the grip one at the front, one at the rear as they exit the gearbox that way. I doubt the gearbox exit holes could take two wires.
Looking at your pic - both wires run up the rear of the grip.
I have a few more work emails to do, cook dinner, take the boy drumming, possibly walk some body else's dog (that's four times now ffs), then I can have a look at the pew.