Technique

Step 1. Select prepared wool texture player model skin version downloaded from device browser or customly cropped version of wool texture.

Step 2. Select Alex (Example) skin to cover up wool texture Minecraft skin displayed in 2D format.

Step 3. Shift transparency tone appropriately to see through wool skin texture beneath Alex.

Step 4. Combine the skins files altogether to become one file piece, then tune saturation, contrast and brightness sections only to a suitable range.

Note: Same with all other material/objects textures of Minecraft model skins that's supposingly white and grey, vice versa for Classic/Steve format textures.