Through the Stick cut out
The cutout in the center of the spar for the control stick torque tube has enough space around it for a wire to pass through and be secured on either side. I'm not sure if you are referring to forward or rear spar, but alternatively you can also run them through the fuselage frames by putting small holes just above or below the rudder cable runs, and install grommets. That is the route I used for a smoke system wire and feed line installation to the baggage compartment in my RV-4.