How to Automatically import external images to Upload

Question

Hi to all I would like to have a simple plugin, hook, anything that Automatically caches external images. Simple explanation: Actually I'm using this plugin: http://wordpress.org/extend/plugins/cache-images/ But with this I have to click on scan, then choose which images I would like to save then wait and so on... I'm in need of something more automatic. Is there anyone who can teach/tell me how to do it? Thank you!