There are corsets designed specifically for men. Google "men's corsets" and be delighted.
Keep in mind, though, that any flesh which gets squished or compressed will go -somewhere-. Be prepared for a bit of extra you at the top and bottom of the corset/shaper.
ULTROS [Final Fantasy VI] (30%)
Haydee Tebelin (manga) [Gankutsuou] (10%)