How do I get multiple cursors throughout OSX?
Multiple cursors isn't a feature supported by Mac OS X by default. Some apps have it and if you want it in the rest of the system you will need too find an third part plugin.

I think it would be hard to make that work even with a plugin. But if you haven't already I would recommend giving Google a try in finding one.

Here is a link to an similar discussion on Super User: Link