Hmm, oh btw, welcome to Acimods! XD
Anyway, I think it's possible, as long as you use the gameboy advance cartridge part of the motherboard to power the LEDS up. That's the only place I know of that will really light them all up right. Then you have to see if you are using different colored LEDs, because red and blue don't go well apparently (I'm guessing for their difference in use of voltage). If you are using like one color for all of the LEDs, then just connect them to the pins 2 (from the right) and 3 (from the left) in the GBA cartridge. If it doesn't work, then switch the wires on the pins. If that doesn't work, then the wiring is wrong, but to me it looks Ok. I think the negative goes to pin2 and the positive goes to pin3, I'm not too sure as I haven't tried moding my cart or cartridge in a while.