It's a bit complicated.

You'll need to create an XSL merge file to merge your changes into res/islands/island4.xml.bin (by hand; GooTool does this for you automatically), set your goomod type to mod instead of level, and make sure everything's in place. Theoretically it's easy except for the XSL part, since XSL is quite a bit more terse than XML. You can use davidc's XML diff tool if you don't mind the result being impossible to read. Of course, if you haven't done a lot of by-hand goomod editing, it's quite a lot more complex than using WooGLE. In my opinion, ISH vs. non-ISH signs aren't so big of a deal that your addin has to have ISH signs if it's ISH themed, but that's just me.

Thanks MOM4Evr really liked your "Undiscovered Information Superhighway".

DO you think you or someone else could give me a tutorial in great detail of what to edit and stuff? thanks for your help.