To be honest with you, I wouldn't even bother...not for just 4 days. Feed em' well before you leave, and they oughta be fine. I've never used those automatic feeders, so I can't comment on them, but I'd be more worried about too much food getting dumped into the tank and polluting it!
Your fish could probably survive a good week or two without food. Now, if you have fry, then that's another story.
Big Vine