Press refresh when you start the project or it will not work. Change the color in the bottom left. Make sure "editing char colors?" is set to 1 and click on the character to draw. Use the arrow keys and "char scale" to move and resize the character. As you will see, the colors you chose will follow the character and appear attached.
An idea I've had that someday I would like to test on a real game. This is a test to see if it would work in Scratch, however I do not plan on using it in a Scratch game. Each pixel is a clone that can be changed in color, but follows the main sprite to appear as if it is attached, allowing for characters to be customized without pre-made attachments.