To start, this is my first how-to, so please excuse the omitance of some things. I tried my best at making this legible and understandable.
I've tried to take as many informational pictures as possible since everything is installed and I wasn't planning on doing a how-to in the first place. I took weeks to decide on placement, what light to use, wires and wiring routes. Change it up if however you want, just note that the door handle will be permanently altered using this method. All materials came from Ace Hardware.
Materials:
Single LED accent light or similar
Butt Splice crimp connectors or Terminal Splice connectors (your choice, I used both)

Wire, 40 feet (I used doorbell wire)
Electrical tape
Tools:
Drill and drill bits
8mm socket with extension and ratchet wrench
Wire Crimp/Splicer
Flat head screwdriver
Phillips screwdriver
Time:
I took two weekends. One weekend for the rear doors, one weekend for the front. Analyze what you should to do next and take you're time. PATIENCE.
Disconnect the battery. You're going to need to remove door panels, pillar covers, and the headliner. Take the headliner out and do each door as a separate entity. The B pillar trim does not need to come off completely, just make sure you have enough slack in the wire so as not to pull and strip (and potentially short/ground) them. I had one instance where this happened and I just wrapped the stripped part in electrical tape. I'll let you decide how to run the wires, but straight up the A and B pillars is probably the best/shortest to the roof.
After removing the door panel and peeling back the weather cover, release the door unlocking stem and use the 8mm socket to loosen the screws attaching the door handle. This is the same for all door handles except the driver's door which has two unlocking stems: one for the handle, one for the keyhole.

Once the handle is removed, clean it up if you want and analyze where your hole placement should be. The LED from superbrightleds.com sits under the handle with enough space for the handle to glide over it. Drill one hole in the handle itself and one where the wire will be coming through. These specific LED's are waterproof which was the defining factor in why I picked them. They have 3M adhesive on the back of the LED and I secured the wires from tugging or movement by taping the wire to the inside of the door handle.

After carefully reinstalling the handle, run the wire along the door. I used tape to attach it to the door. Next is the hardest part of the whole install and where patience really comes in to play. The rubber connectors the allow the wires to run through the door and in to the cabin will either piss you off, or be complete cake. After the first one I did, the others were not to bad, but the rear doors are easier than the front. I would have taken one off to show you, but since things are already installed and I had to figure these out on my own, all I can say is good luck. The door half snaps off and the cabin half is held in with snap connectors. The rubber will slide off and you'll see what I mean. When doing the rear doors, close the door and do things from the front seat. When reinstalling, the connector sits in the rubber part then snaps in to the B pillar. It is easier to pull the wire from inside the cabin to the door.


Once the wire is through and you are satisfied with the slack and such, hook the wires together. REMEMBER: Take care in making sure the wires are not pulled on by the window being rolled down.


Bring the wires up and prepare to keep track of your mess. This is the wire to the dome light. It runs up the drivers side C pillar. Pink is positive, yellow is negative.

I used the splice connectors the first time, but the drivers side door didnt work at all and the passenger side would flicker at times. So I chopped the old setup, stripped the wire ends then crimped the wires together. The rear doors are still connected/working with splice connectors. I turned the map lights in to my dome light so those wires are optional. For those wires, yellow/black is positive and orange/black is negative.
Old

New

The final clean up. The wires closest to the rear of the car are the splice connectors to the rear doors. The wires closest to the front are the the crimped connectors to the front door and dome/map light.

Success!



Questions and requests for pictures/information will be explained as much as possible.