Extract custom mod?

Thanks to info here, extracted GD/AoM/FG, no problem. Now want to
extract some custom mods. Say it’s “modx”. Would it go like this:

Working: Grim Dawn\Working
Build: Grim Dawn
Tools: Grim Dawn
Additional Browse: Grim Dawn\mods\modx
Additional Source: Grim Dawn\Working\mods\modx\

If not, how to do it? Also, would it re-extract all the regular GD files? Would like

to avoid that, if possible. All help appreciated.

Read here:

Thanks for the link. Still trying to get my head around the info. Wondering why the regular method (for AoM etc.) doesn’t work. Anyone know?