Salvete! With Adobe InDesign, it is easy to create custom menus using extendscript and simply drop it into your Startup Scripts folder – you get custom menu commands that way and it works like a charm.
How can I do this for Illustrator? Maybe it is there, but I can’t find any menu methods in the Object Model for Illustrator, and the same script that I use for InDesign won’t work for Illustrator.
As the DOM seems not to offer any access to any menu object, it looks like a deadend to me.
As for dropping indesign scripts within Illustrator, it’s no suprise that it doesn’t work. Both applications have only a very narrow set of common objects.