Make sure that the LEDs you buy are the voltage of your vehicle!! They sell 12V and 24V out there so make sure you choose the right ones.
Here is a helpful link:
12V DC flexible LED ribbons (I call them strips) I used in my installation, remember the Strips can be cut into 3-LED segments
Doing this may damage some of your parts as the old plastic is very brittle, so I recommend getting some spares from your local store and working on those.
Step 1: Under-dash lights
-paint stick or similar
-cable (zip) ties
Step 1: get a paint stick or something similar that is long and stiff (ha), make any necessary cuts and holes for proper mounting. I just used cable-ties for mounting, it's cheap and simple.
Step 2: With a soldering iron, make some leads on the LED strip so you can later connect it to a power source.
Step 3: Stick the LED strip to the paint stick and mount it underneath the dash.
Step 4: Find a power source (i used the socket from the stock lights) and tap into it somehow (crimp, solder, or whatever works for you)
Step 5: Some LED strips have to option of red, green, and blue, all on the same piece. if you want to be able to change the colors, all you need to do is make some switches wherever you want and have the leads going to the LEDs.