How to change r.sss.checkerboard???

I’m having an issue Unreal is well aware of and hasn’t fixed yet where subsurface materials break and ignore the color map, turning things white: Unreal Engine Issues and Bug Tracker (UE-41814)
The say that it can be fixed by “simply” changing “r.sss.checkerboard to 1” and the issue will go away, but I’ve looked for hours, and while I’ve run into this explanation 2 or 3 times, NOTHING explains where this setting is located or how to find or edit it. I’ve asked repeatedly, no response, and my previous attempt to post in the forum was deleted with no explanation before it was posted. Reddit didn’t answer at all, and I’ve spent hours with no result. Where the hell can I find this setting??? I’m not incredibly experienced with Unreal, but for so few results besides answers to this exact bug, this is either buried in code or internal settings, or assumed to be so ubiquitous that no one ever mentions it (even though I’ve checked documentation, tutorials and beginners explanations as well, so it clearly isn’t).