The leds in those knobs I just used 5mm Diffused RGB LED Common Anode from ebay.
The leds in the dash with the speedometer and whatnot is a diff beast. The current leds are some very small 0603 smd leds. There are no rgb leds of this size so I had to put a little thought into that mod. What I decided to do was get some 5050 smd rgb leds. I removed all the old leds and used some very thin wire to jump all the new leds together running the grounds to my controller and I hooked the power up to where the existing power was at. This way whichever light that was ment to be on would come on. I then used a small amount of hot glue to attach the new leds in the spot where the old ones was at.
I have been doing this with a used cluster I got so that if I broke it I wouldn't be destroying her good one. After I get it 100% I can easily remove the leds and transfer them setup to her real cluster.