Media Gallery Columns, want just 1

I’d like the ability to choose 1 image column when attaching a gallery via the media library to a post. I know the code that handles the media library is in media.php in wp-includes, but I’m not sure how to go about overriding it in my child theme functions.php. Any help would be most appreciated.

Basically I want the gallery to be one image showing at a time + pagination to the next, just like when you click one of the gallery thumbnails, when they’re in columns, and it does just that. Is there a way I can bypass the first part all together? (first part being, where the columns show in the post) Thanks!

*Using WP 3.0-RC3