Just the brush? Good working, there.
Back when I used to do this for other comics, and I'm talking 13 - 14 years ago, we used a couple of programs called Colorize to pick out separate each different objects (man's skin, clothing, eyes, hair, etc) for everything on the page, importing the colours in to Photoshop, then import the linework as a different channel.
It was a massively drawn-out and elaborate scheme, but this was using Photoshop 3, which is probably about 6 versions behind now, at least, and before Layers were the norm. It was always a lengthy process, but some of the stuff was well worth it.