BF poo i just put in the wash - its all liquid anyway so a pre-wash is all you need to help it along.
Once it got a bit stickier/thicker with formula/weaning later i used to just pick off all i could with tissue and flush it.
Once solid it just rolls...
I have never sluiced a nappy and tbh, never would - its not really needed if you have a good machine and a pre-wash.
Pick off all you can thats lumpy/thick and let the machine do the rest of the hard work. Modern machines and detergents are very good at cleaning and as long as there are no solids it'll all come out fine.