well the thing about LEDs is that you need a lot of them to light up the whole case, and when i say a lot, i mean a LOT, and A LOT, AND A LOT. im talking about 10, maybe more LEDS for both front and back, otherwise it'll look dim and there's going to be shadows everywhere (the fins of the heat sink tend to block lights and make them look bad..). the wiring is going to be a lot messier than neons.
you're best bet is to use UVLEDs, or neon lights, and personally i think neon lights will look definately a lot better than just LEDs or UVLEDs, coz you can actually show them in front of the window, not like you'll have to hid LEDs somewhere coz their pins and wire ruin the whole look of the mod. :P
PS: hope you succeed. post some pics after you're done.
matrix infinity: on and off 6 times
external speakers /w leading wire: done
memory card LED (activity + connectivity): done
controller status LED change + vibration LED: done
color-change lighting in v12: done
rgb to vga for monitors: FAILED due to not enough material
portable/internal LCD: sadly failed, as ps1 screen doesnt fit. planning same mod with intec screen
external harddisk for v12: CANCELED due to v12 breakdown
window for ps2 dvd-drive mod: in progress