Did you figure this out? I'm trying to wrap my head around it to. Can we just use arbitrarily named miners on a remote pc with our main account private keys and it will give it to that witness? I'm worried the miner instance will solve a block and then not know which witness to give it to.

It seems like the goal of trying to up your hashes and odds of hitting a block for the same account by using multiple machines isn't really feasible.