it isn't easy, but...

you can add " -d 0,1,2" to algorithm command lines for the various versions of ccminer, each of which you have to set manually, each of which can be found in the "Miners" folder and edited via Powershell.

for EWBF, you need to set it as "--cuda-devices 0 1 2" with each integer being one of your devices, starting at 0