Simply create an overview with only the ore you want mined.
There was a way with the old implementation from what I read (Sanderling), don’t know if anyone made it to elm. Getting the drones to start mining can be simple, by pressing F with the asteroid locked and selected (pressing keys described here). The old sanderling post that identifies NPCs (can be helpful to decide which drones to launch and when) can be found here. Still, as I said, the bot is built on elm now.