Thanks for the comments, i know im still nooby compared to others, but there is perfect space in under the powerboard/battery cover spring place to one 5MM led.
UMD assembly removed so no any problems with led in there. And under the wlan chip is the third 5mm you probably know theres some good space.
At first i would have used color-changing RGB's instead of those greens but i just liked the green that moment
Theres also a switch in the UMD door what switches these off, but camera is so crappy in close-up shots i didnt even try to take a picture...
Edit - what color leds would you suggest for led swaps? I Think i'll keep the power as green.
Also it will have the CFW, of course.