so how does one go about creating new graphics to match elements from the older one, considering it was created by someone else?
Some times depending on what it needed you can use existing images to fashion a new piece. Or start trying to build a new part with applications like Paintshop,Gimp, etc.
You can try here for Tutorials on skinning and such.. WC Wiki
And Yes I would attempt asking the Author if possibly they may be interested in helping or at least offering permission for you to upload the updated skin.
Have fun and keep us updated