Deselecting Standard Modpack Components?

[MoarPye]

If I'm installing a Standard Modpack (i.e. one with no configuration settings) that replaces, for example, 4 different rings but I only want it to replace 1 of those, with TexTools I can just uncheck the files associated with the 3 unwanted rings before I click 'Import Modpack'... Et voilà! I've replaced just a single ring.

How do I achieve that with Penumbra? Because I've been struggling with it for two days now, making the mod editable, creating my own configuration groups, adding files to those groups, all so that I can simply deselect them... But even that doesn't seem to work... I still only get all of a modpack, or none of a modpack?