What this means is you can take a mannequin model, put clothes on it, and use the plugin to transfer the weights to the clothes so the clothes will move with the body. Several people put up tutorials on how to use the plugin. Someone scripted a plugin that transfers weights from one skin to another on the rigging, which basically saved my life here even though the plugin is in Japanese. Not just artists, but computer minded types, who are willing to share their knowledge.
Turns out there is quite the community for this over at DeviantArt full of many talented people.
Sifting through page after page over at LearnMD and DeviantArt, reading one tutorial after the next, I’ve been able to figure out how to customize my very own 3D model for the MMD program.