ammmm.... Sorry i didn't quite get it, using resolution from source file and map and smth!????????
Look, Game Folder > FOF_Data > StreamingAssets > clothes.
There is clothes textures.
To make ur own choose next folder: A1 - Panty, bra. B1 - Gloves. C1 - Tights. D1 - Pants. E1 - Top. F1 - Shoes
Each chothes folder contain UV folder with UV map. UV map is how polygons gonna lay on char.
Next. open Photoshop or another pic editor and make this. Top layer - ur clothes and where you draw. 2 layer - UV map. 3 layer - gray background (optional)
When you done delete 2 and 3 layer and save with name - [clothes folder(E1)]_[Free number in folder(15)]
Hope you got it
Done