Thanks for the reply! The thing about it, is that the AVRCPAgent is replaced by something else in 10.10 now, so I've been able to run it kind of on the side. It's definitely a hacky solution, but that's why I brought it here to hopefully get some advice.

Hey guys, I implemented a last.fm scrobbling that you can check out here: http://jamesfator.com/blog/2013/05/17/google-music-app-for-m... If you're interested, check it out and let me know what you think.

Just installed it, works well!