You can use the new macro (or make your own macro since events don’t need arguments anyway), but otherwise you’d need something to copy-paste the code snippet around, be it by hand or automatically - GameMaker does not currently offer anything that could be used to prepend code into places without modifying the files.
The cornerstone of the extension’s function is that live_call figures out who’s calling it, whether there’s a new version of that event/function loaded, and returns true after executing it if so.
GMLive is by all means a pretty big extension, but it does not do any sort of black magic (compared to, say, my most recent extension)