No - feeding prey too large will not break your snake's ribs - that's the silliest thing I've heard in some time! LOL
It's not good to feed too large, because it can cause regurgitation.
No "tricks", no stunning, no holding with tongs, or dangling by tails is needed.
Pre-scent by putting the mouse in a critter keeper near the snake's enclosure for about 30 minutes, then drop the mouse in the enclosure at the opposite end of the enclosure from the snake, and the snake will take care of the rest.