Messing with the Create New Gallery screen

I’d like to be able to launch the new Create/Insert New Gallery screen from anywhere in the back office and retrieve whatever images a user has picked for his/her new gallery. This is because, in the end, I want the user to pick some images so that their IDs will be stored in some post’s metadata, instead of just inserting a shortcode inside the post’s content.

Now, as WordPress uses Javascript for most of this, my usual method of looking for actions and filters didn’t get me too far. 🙂 Any advice on this? I haven’t found a lot of docs on the new Media features yet.

Thanks.