Hello My little Oliver is nearly 5 months and f...

Hello My little Oliver is nearly 5 months and for a variety of reasons I would like to start weaning him. We've had no success with the bottle (chews it like a piece of meat), so several people have suggested sippy cups. I'm having a little success with these, but he's certainly not interested in taking a whole feed from these. Should I be 'mean' and not offer the breast at all (which is what I do when he gets all upset) or just try and get him to take as much out of the cup as possible, and then give the breast? I need some help!!!