Hello DIGItonium,
I really liked your idea and your detailed DIY post(s) regarding the Interior LED Color Change, it was very helpful. I did something similar and figured I would share. My notes are not as detailed as yours and hope it is enough to assist if others are thinking about it.
I found some LEDS in Red & Blue at local electronics place (FRY's Electronics). For now i only did the speedometer and tachometer and am debating to tackle the rest. They are made by Linrose,
Linrose Electronics Inc.. Each strip cost about $20 bucks and they come with 26 LEDS with SMT current limiting resistors, no extra stuff required. The led flex strip comes with adhesive tape on the back so you can just apply to the inner space underneath the gauges and tie to 12V (key on). You can add a potentiometer as a dimmer or tie into factory dimmer. All factory LEDS left in place, just added the new ones. Soldered on some wires to the strips and ran to the fuse box to a 10A "ignition on" circuit lower left driver side. I made note of where the instrument needles were "at rest" so they are not out of calibration when I returned them. I used a fork to pry them off with a microfiber cloth to avoid touching the overlay. As long as you go slow they will come off, they are on tight and the secret is to apply pressure evenly when removing them (go straight up) and watch that you don't bend the needle side ways when lifting up on them. Try not to touch the inside of the clear plastic covers either. If you do then clean them and look at them from all angles to ensure the cleaner did not leave any haze. Total cost was 40 dollars and install took about 2.75 hours. The only thing I noticed when I was done was that the passenger airbag warning light was blinking and the center console was indicating it had been turned off. This was a result of disconnecting the instrument cluster. To resolve this I had to reset the computer by following a procedure another forum member posted. Search for key phrase "reset airbag" and you will find the post. Resetting the warring indicator is very easy to do, 20 second procedure. Removing the battery cable does not reset it.
Regards,
370Z1