A fairly simple, straight forward mod. you'll need a bit of soldering, painting, and basic tool skills.
Step 1: The Teardown.
I won't go into detail on how to tear
it down, because there are numerous sources online on how to go about it. You'll need a gamebit driver for the unique screws Nintendo uses, I used the plastic pen method. (heat plastic pen and press onto screw making it into a driver)
Once you've stripped down to the board, you'll see there are 12v, 5v, and 3.3v rails marked throughout the board.
Step 2: Replace Stock LED, and Add Lights of Your Choice.
I added 5mm white lamp to the 3.3v rail near the controller ports to replace the stock red. Also take this time to pull off the N64 plastic logo, and dremel out the plastic behind it to allow light to come through.
I then soldered a clipped piece of LED leg onto the ground rail, giving myself a common place to ground my blue lamps, with their source being from the12v rails on both sides of the board. I placed two on each side near the vents, two under the cartridge slot, and one behind each controller port. To make light cast more evenly, I applied a coat of hot glue around each bulb to diffuse and secure them in place.
Step 3: Paint Whatever Color You Desire. (optional)
I used Valspar primer for plastic, Valdpar outdoor radiance colors, and valspar gloss and satin clear coats. Trust me, you'll be excited to mess with the unit, but I learned first-hand to be patient between coats, and allow plenty of drying time.
The controller is simply parted down, masked accordingly and painted to match the console.
Step 4: Reassemble, Test, and Modify.
Take caution that your bulbs do not cover any of the screw holes, or points of contact between the two halves. Once you're comfortable with the reassembly, replace your screws and reassemble your controller.
Step 5: Things to Keep in Mind.
The solder pads and pins are very close, be careful not to bridge any together.
Do not modify board at any point while it is on, you'll want to test it frequently during the build, but if left on during, you risk shorting out a crucial rail that a lot of people have noticed frying the entire A/V system.
Insulate, and fasten your connections. hot glue is my go to electronics adhesive, its fast, secure, insulating, and best of all, you're able to easily undo it if need be.
I'm sure I've left something out, that will be caught after posting, and I'll make every effort to fix it if need be.
Step 6: Thanks Guys, Enjoy My First Instructable.
I've been a long time electronic tinkerer, and a long time instructable lurker, I take pictures of every project and finally decided to post one. Hope you enjoy, and any feedback, corrections, or suggestions are greatly appreciated.