I saw a very similar tutorial for Sai in Pixiv. So I decided to make one for Photoshop as well. ovo/
I'm sure there are other ways to do this, but this is the best way that I know how to do. So yeah. I hope this will one day save someone's agony.
Or at least it's a good info to know??? IDK. I tried to help. ;7;
Program used: Photoshop CS5