Like Jorge and Tim already mentioned, corns don't need those extreme temps to brumate, and many breed successfully with hardly any cooling. Even certain much cooler montane species only need around 50to 55 degrees for brumation.
Your corns would be FAR better off(and much safer) being brumated in the 60 degree area of your house. The 40's is simply too extreme and is asking for big health problems, and even death.
They only need temps to be cool enough as to conserve their body mass by slowing their metabolism from expending energy, and 60 degrees is plenty good enough. Just make sure they have NOT been fed approx. 10 to 14 days prior to gradually lowering the temperature to ensure there is no food in their gut that will putrify and poison their body.
~Doug
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"a snake in the grass is a GOOD thing" 
my website -serpentinespecialties.webs.com