To give you an idea of how easy it is I'll walk through the wiring diagram which I pictured here again. Inside the cab you will have a switch (it is provided in the KC light kit) you can mount it where ever you want.
The switch will have three post on the back of it. In the wiring diagram see the yellow wire...that is 12V keyed power, meaning it only is live when the key is on. The easiest place to find that wire is (on a 97-02 model TJ) behind the glovebox. Jeep provided two leads back there for the purpose of wiring up accessories like lights, etc. I pictured it here also. The blue wire is keyed power. You would run, with as much extra wire as is needed, from that blue wire to the back of the switch on to post #1 (its labeled "LINE" in the back of the switch). That is the "yellow" wire for our purposes. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
You need to now ground that circuit, so with another wire (black in the diagram) you would go from the back of the switch off of post #3 (labeled "EARTH" on the switch) to any metal part of the body. There are numerous places to do that, off hand i would say go to the braided ground wire located behind your radio. We now have the switch circuit wired...if you flipped the switch right now, the switch would light up but nothing else would happen. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
We need to get power to your lights, controlled by that switch. So we will run a wire from the engine area, where we will locate your relay, into the cab up to post #2 (labeled "LOAD" on the back of the switch.) The easiest way to do that is through the spongy foam located on firewall. I posted another pic of that area. You can see my screwdriver poking through it (red and black handle)
I say run the wire from the engine area to the switch and not the switch to the engine area only because in my experience its easier to push the wire into the cab and fish it out from behind the glove box, than it is to go from the cab out to the engine, there just to much crap in the way to even get your hands up there.
Once that engine bay wire is run, and connected to the post #2 on the switch, we are done in the cab. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
To recap, we have three wires, one is from the blue keyed power wire from behind the glove box to post #1, one is from post #3 to any metal, and one is from post #2 out to the engine area.
Now a relay has 4 posts on it. they are labeled #85, #86, #87, and #30. Your kit will have a plug that fits that relay, and you will notice the plug will only fit one way on it. Plug the relay into it and let it be. The post number on the relay are labeled next to them underneath. make note of them and what color wire KC uses for each post.
Our wire we ran into the engine bay from the switch will hook up to the #86 post on the relay. That part is done. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
from the #85 post on the relay we will take it to ground, anywhere on the sheetmetal, off hand on the passenger fender there are a few grounds (screws with a black wire going to them). Now that part is done. We only have two more wires to go. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
Lets concentrate on your lights and their wires. From what I can tell from the KC pictures they did the hard part for you and the four power wires and four ground wired are all just plug in. Plug the red to red and the black to black on all the lights. and you will be left with two wires coming down from your light bar. A red and a black (don't get to hung up on the colors i am using, KC might use different colors, but the will be labeled power and ground, in my scenario red is power and black is ground) The ground is easy, find a out of the way spot on the metal body and place it under a screw or bolt. Look around and go for easy but un-noticeable locations. you can use the same location as the #85 ground you just ran if its easy to get to. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
so now the light bar has its ground, lets move to the power wire.
It is going to hook up from the power wire (red) from the lights to #87 on the relay. nothing more to it. That part is done. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
all we have to do now is run a power wire from the positive battery post to the #30 post on the relay.
This power wire will be supplied by KC, and it will have a inline fuse in it already, try and place the fuse within 20 inches of the positive battery hook up, meaning no more than 20" of wire from the positive battery post. (Its just common practice to keep the fuse close to your power source) KC will most likely have less than 20" from one end of the wire to the fuse anyway. STOP RIGHT THERE, YOU ARE DONE WITH ONE PART OF IT
you are done. go turn your key on and flip the switch. at this point you can ziptie all the wires neat and tidy up your connections.
Every set up will be different so i am not sure you are going to get a exact video of what you want. I tried to explain it all without to much tech stuff and basic starting and stopping points.
If your wondering, the relay is like a remote controlled switch. the switch you put in the cab controls the heavier duty switch between posts #87 and 30 in the relay. its a switch that controls a switch!
Or if you want, buy two sets of lights, have one shipped to me, and i'll shoot a video of the install...but I keep my set of lights