Okay, well I managed to create my modified icon...and really once I found the code section I needed (props to Zuban, the fact that it was quite easy shows that his code is well laid out) and then create a new texture variable in the Object code at the top.
Honestly, I think the most frustrating thing was finding the right icon...Blizz really needs to provide a good reader for those .blp files
Still hoping to work out a way to switch the icon upon alt press but I don't think this language supports multiple threads or polling, heh