Image uploading hook for plugin

I’m interested in passing a URL and title to some function to easily input a remote image into the WP database as you would with the regular media uploader… unfortunately I have found no such function. Anyone know of any examples of this kind of simple functionality in existing plugins?

The long explanation: I’m pulling image URLs via XML requests to an API and I would like to have these images saved locally for use in WordPress posts… I’ve seen some round-about ways of making a new user interface to accomplish this kind of thing but I’m looking for something more direct: specify an item in the post panel and have all the back-end work processed automatically. Any help would be greatly appreciated 🙂