They were pretty easy to do. Depends on how you want them to turn on? you can wire them to turn on when you interior lights are on, or you can run more wires and add a switch. I have added a toggle switch on the dash I was going to place it on the center console but figure it would get bumped, and when I started the work found it just worked better by the dimmer but also so I could dim them. Here is a switch I used had to cut the back plastic just a little.
Scion OEM Style Rocker Switch
Here is a link to the LED's.
Tiny Prewired Super Bright Surface Mount LEDs - 12V DIY Plug and Play SMT LED
They come with a 3M sticky back and inline resistor they are pretty small no heat and the wire to them is so thin you can tuck it through the gaps in plastic. They come in lots of colors. I placed them on the back side so you don't see them just the glow.
The light in the center console glove box is this.
12V LED - Pre-wired Waterproof SuperFlux LEDs
I added a rubber grommet to hold it. And there is a small plastic pop out in that box the factory uses for power supply on some models I believe? Mine does not have anything but the stereo hook up in there so this way I did not put a hole in the box it's self.
One thing I did is find a place to run every wire to and put a small amp fuse I used the center area for allot of the light to wire back to and also have some wired back to a fuse at the switch just under the dimmer there is a little room there as well.
There are lots of lights and makers out there so look at some of the pic's give it some thought.
I'm going to use the small flat LED's to light the speaker grills when I get the time.
And TIME was everything on this mod. Take your time make a good connection because it would be a pain to go back and fix a short or something.
I have found the lights are pretty cheap work great and work even if the voltage is not an exact 12v I was worried at first because auto's run as low as 12.Xv to 14.4v (varies on a few things) Hope this helps some.