I use 3DS Max to create my skinmaps (like the one you posted above) however gmax has similar tools. It just does less of it for you. Normally what I do, is when I select "unwrap UVW" I use a mixture of the planar map option, shown in the image below, and tweaking by hand of the edges (so the textures won't stretch). You can see in the image a yellow box. This shows which plane you will be mapping to. Test it out and you should be able to see how it works.
http://img211.imageshack.us/img211/555/planarmaprl6.jpg)
The key, when making your UV map, is to make sure surfaces don't overlap (unless they will look the same - two sides of a blade, for instance, should probably overlap), and that your textures don't stretch. To ensure this, it's a good idea to find a checkered pattern to put on your model while you're creating the UV map. This way you can see if any of the checkers are distorted, and you can modify your UV map in that area to suit.