Put a bit of seasoning in them -- I'm from the south and we use bacon :-), but only a small amount
'cause we all know about bacon
. Or you can use a bit of butter or margerine. THEN.... get yourself a bowl of green beans and sit down somewhere that the furbutts are allowed i.e. the couch and start to eat them yourself like it is the best thing that you have ever eaten. I mean really smack them up. I bet it won't take very long for your little guy to show some interest. I wouldn't let him have any right away, just make him "watch" you eat all of the good stuff.
My critters couldn't resist trying something that I found so tasty -- I am one who firmly believes that good dog food = good people food. I do feed my guys a super premium dry kibble, but they are allowed to have tidbits of anything that I eat that is safe for them.
If that doesn't work, then try making him work for the "treat". That has also worked for me -- what a great way to fake them into thinking that something is yummy.