Yep. Same general principles apply. The images should be 512x512 or 256x256, and saved with a transparent BG. I typically find the easiest way to do this is to create a new file, then create a new layer and delete the background layer. This leaves you with only Layer 1, which is where you paint your texture, and then when you save it to a png the alpha will be retained.
Alternately, Here is a tutorial
I put together back in the day on creating textures from Photographs, although the links are broken now. Still, if you are familiar with Photoshop the text descriptions might still be of some help.