Custom “Insert into Post” button, in Wordpress Media Library

I am trying to make a simple plugin that sets a background image. I have it linked to the media library so that when you click "Insert into Post" it does a custom function. However, obviously this custom function is undesirable in any other context. As such I would like to make a separate button "Make Background" that would call the cus开发者_如何学Pythontom function. Any ideas?

Thanks

You could use featured image or even custom field template with a upload field, so when you load the page you do all the CSS stuff.