Applying attributes to linked grayscale images - js

I found a way to apply these features by using Graphic Styles.

To bypass the fact that Illustrator scripting doesn't let you create GSs, my workaround is to "load" them into the document by using predefined path items from a template document that resides next to the script file.

It's working, but I don't like this kind of "dirty" solutions, so if someone has a "cleaner" one to offer, I'm all ear.