This information doesn't qualify as a tutorial, but I thought some may be interested in this "tip" on how to create snow textures on custom images like this (crashed escape pod): http://www.x3dmod.com/ftp/images/skyrim58_wreck4.jpg

1. Open your custom texture image in Photoshop (or other capable of working with .dds file format)
2. Paste http://www.x3dmod.com/ftp/images/skyrim_snow.jpg on a new layer
3. Use an erase tool on the snow layer with a brush that gives you the effect you are looking for
4. Flatten the image and save
5. Create a Normal map image and save

Make sure your images have correct alpha channels. It's a good idea to examine the stock images to see their requirements.

Anyway, if nothing else, you may find the snow texture useful.