You don't have to pull down on the headliner much at all to feed the wires through. It's really easy. My only recommendation would be that, if you can, feed the wires from the map light area down to the mirror. It's easier than feeding the wires in the other direction.
That said, I wouldn't tap into any wires in the overhead console at all. I do not like tapping into stock wiring where I can avoid it, plus there's no good spot in that area to get a ground. I tried ti ground it where they suggested in the DIY you're probably using, and even dremeled down that screw head to get good metal on metal contact, and u still didn't get a good enough ground. The mirror appeared to work, but the homelink wouldn't program properly. I would suggest doing what I did, which would be ti route the wires to the fuse box, which is actually an easier install. See post 100 in my build thread and let me know if you have any other questions.
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