Also, you won't really be able to create a universal overlay system that will accommodate every figure. Each has their own peculiarities and mapping, in this I mean an overlay designed for Miki is not going to work on V4 without some scaling and adjusting in an image editor. You can create a generalized texture creation kit for details, make ups, etc, on their own layers that can be manipulated in an editor to fit a particular template. The Edit/Transform and Filter/Liquify Photoshop functions are useful tools for this.