Here's a video, it's pretty simple.
If your bushings are press fit, they can be pushed out carefully using a small socket or rod of appropriate size, from the rear. The trick is not to damage the wood on the face. Slowly, a bit at a time on the first one, then once you have a feel for it, the rest should be no problem. The word is CAREFULLY. You may not even have to do this as there is an even chance that the Grovers will just drop in. I think that is what Epiphone used, until recently changing their specs on the site. The specs for my 339 have been recently changed to the same as your Casino Coupe. Mine's a 2014 so it has the "Grover Deluxe" not the plain "Deluxe" that are now stock. Even Gibson uses the very same Grover tuners just relabeled "Gibson Deluxe" on some of their guitars!!!
Kind of a PITA considering how good the Grovers as originally supplied are!
Good luck with that, you should be fine. Please let us know how it's going, Ryder!