You can use the BCR2k by itself, but to get the Korg to reset all the BCR2k controls when you change a patch you need an Arduino or PC in the middle.
You can have a look at my attempts in this video. It really feels like the BCR2k is part of the Korg
I only have a DW6000, but I rewrote the software to work with the DW8k
All the best
Royce