ground is connected all around the chip
but just to give someone inspiration if they have a "faulty" but working motherboard lying around (say something like ripped card slot pads where someone tried to replace it and messed it up or something, that still boot up, but is otherwise unusable) that they don't mind using as a guinea pig, here is the genral idea
that was done on a nokia n95 to replace the emmc, as you can see they had also removed the old chip....obviously there is a bit more room to play with in the 3DS though
That's really interesting.