I had Save as … (encoding) commands in the main menu at a certain beta version, but some people (including me) found complicated, and even worse, deliberately chose a Save as … (encoding) command where they meant to reload with a correct encoding, and ruined existing files. That is why I hid these commands into the All Commands, but you can easily define your menus.
document.UnicodeSignature = false;
You would be able to assign this macro to a menu item, and insert the menu item to anywhere you would like.
Thanks for your nice comments!