The way I'd do it is by opening up the head skin file into PMC and then removing the body with the eraser. Save that file, then open up the body file into your editor. To the right of the "pixel brush", there should be 3 dots that you can click. Click "import image as brush" and import the head file you saved (with the body removed). It should appear near/beneath your brushes, and just click it. To line it up with your body, I personally go into 3D/2D mode (on the upper right of your screen right underneath your profile picture) and add it there. Then just save that file and you can use it
