Open up the text editor, go to Core.SC2Mod and find "Custom Resource" from there including the others.
I'd say that you should be able to import a new image and overwrite the old like in WC3.
I gotta say I loved those maps. I don't mean to gloat, but I at one time new miyog and his fiancée iyog.
I'm currently looking thru all the native functions and getting a feel for galaxy code. I've done small things in c++ before, so working in a c based language shouldn't be to hard. I'd be glad to join the project and help out, but anyways I'll try to message you later unless you answer to this post.
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