Its not too hard. Pull the door boot off the door and body, get a wire fishing tool, gopher tool or a long ziptie with the end cut off. Fish that through the boot, then tape your wire and pull. Some wire lube, windex, oil, lotion, whatever you have laying around LOL will help if needed. Just a dab on a rag and rub down the wire if it starts hanging up.
I pulled wire to the doors and dash on my 08 coupe, will do the same if I decide to put a stereo in the 09 ********. I did it all by feel, didn't lay down in the car at all, it wasn't bad. Just make sure you get the door boot snapped back into the body correctly when you are done.