Normal.dotm is not the way to distribute customizations. It should not be shared.
Use a separate Global Template. Methods for sharing such a template are on the linked page.

What you are talking about, I hope, is a button on the QAT. This is not normally called a "macrobutton." That modification should be stored in the same template as your macro; no ribbon modification is needed to do this. This is easy to do and requires nothing outside the tools built into Word.
Modifying the Quick Access Toolbar (QAT) in Microsoft Word

Here is information about the different MacroButton Field.

Custom UI Editor works fine for all ribbon versions of Word. I currently use Office RibbonX Editor, which is also free.


General rule: Just about anything that works for Word 2007 works in all later versions of Word.