I would use Cat5 and install it just like a motion detector (even use a covert PIR cam.). Use a 18" 3/8" bell-hanger bit to start the hole, then switch to a 4' flex bit to drill all the way up. Hopefully you can pick a spot where the 4'er will pop-up under carpet in a closet. Then carpet-run it to the nearest wall and tuck it under the space between the tack strip and bottom plate. From there you can just expose it up to the attic with staples, or hide it in the wall if you want to do it nice.
If the bit pops-up in a bedroom or hallway, then just carpet-run to the best interior wall to gain attic access.
Plan the drilling first, go up and down a few times to verify you won't be drilling though tile or any furniture. Stay away from bathrooms, wet bars, wood floors. If you don't want to drill through carpet (it wont hurt normal carpet, but will destroy Berber Loop) peel it back first, then you'll need to re-stretch it (I can do it without a carpet-kicker if it's just a little corner I peeled back), just jump into it like a kicker would do.