From what I've been able to figure out, both brumation and photoperiod play a role in stimulating breeding. Photoperiod can do the job alone, though. That's why you hear about so many people getting breeding without brumation.
If I wanted to keep a female corn snake from breeding, here is what I would do. Put the snake in an aquarium-type cage. Get a pair of 2-4 foot Vita-lite fluorescent tubes (or similar full visible light spectrum tubes; UV does not matter). Put the lights right outside the cage for 16 hours on per day/8 hours off per day to simulate the full summer portion of the light cycle. Next August go back to the normal light cycle.
The most likely problems would be skipping of two breeding seasons rather than one. And other snakes should not be exposed to the female's light cycle as it could prevent them from breeding, too.
Good luck.