I agree. That's why I was originally hesitant on posting the link. The original topic was rounding corners on a NURBS cube which is why I posted it. Anyway, have you tried converting your poly cube to subD (or poly proxy mode) and working on the corners that way? Might be an option if you're not getting the desired result through beveling.
"Terminat Bora Diem, Terminal Auctor opus."