Added addition "featured" elements

I’m trying to build a plugin which will implement the following functionality. http://cl.ly/image/3R1r270y430w (note, this is just altered dom, that link is not actually there).

Are there any hooks I can tap into to use the media screen in this way? Basically I just need to let the user select an attachement id and assign it to a custom field (like the featured image implements).

Alternatively, is there somewhere in the wordpress source that I can “copy” the native implementation of featured image, or a plugin that does something similar?

Any help would be much appreciated.