Welcome to the forum!

Even my adult doesn't like to eat whole pinkies because he's picky :P If it's small enough to be in a 4.5 gallon, you're almost definitely going to have to chop the pinky for it... And like others have said, scent it with fish or mix it with nightcrawler bits or something. Chicken (or birds of any sort) aren't really a part of the snake's natural diet, so that wouldn't help him recognize it as food, plus the salt is bad.
Do you know what (or if) it was eating before you got it? That's usually a good place to start