main link in gbatemp is here :
https://gbatemp.net/threads/wii-u-hardmod.413847/
basically the mlc is easy to dump (similar to 3DS hardmod) but the few posts that i read here and there report bricks and never got a clean explanation on this one
The slc seemed to be dumped with a teensy by smea, i guess through low level open nand interface (like ps3 tsop).
the seeprom is located inside the latte (i think ) and can not be accessed without chip destruction ;(
Still don't want to break the wiiu , waiting for a crystal clear tuto for this, don't have the smea & co guts