Hmmm.... not as easy as it might sound Lee. It can be done, but once you start stretching and tiling the various parts it could look a bit odd. Much better to just take your color pallette from your wall, and make graphics that will perform correctly in WB's.
For example: I am going to make a WB skin to match my "Loves dying embers" wallpaper, but if I just cut out a panel from the wall to make into a titlebar, it will get screwed up when tiled and just look messy. So I will make graphics that match the colors in the wall instead.
If you send me a screenshot of the wall you are considering using as a base, I will take a look and tell you if you can use any of it in your blind. Worth a shot eh?