I used a small electrician's fish tape to push a channel in the Reflectix layer of insulation between the rat fur and fiberglass. Work slowly as it tends to come out of the rat fur, esp at curves.
Pick up battery
and return from inside overhead kitchen cabinet (lights wires run under tape in outside bottom edge of cabinet).
What I did was use template outside to mark corners, drilled small holes in FG at corners and push nail thru rat fur. Inside, I cut the rat fur and Reflectix away so I could drill larger holes for saw blade (some have used roto-zip). Be SURE to not cut away too much rat fur as you will want to tuck it under fan trim -- More rat fur is better!!! Also be sure not to let drill or saw blade touch rat fur as it will wrap and pull.
Alternative to fish tape is slice rat fur, insert wire and reglue -- Likely messy.
Alternative is run wire on surface, cover and hold with long strip of rat fur with hook-side Velcro glued to back.