How cold? Once you get them coming to a specific spot you can just throw the raw corn on the ground or do as I do and dump it in shallow holes and cover with flat rocks. Covering the holes with flat Rocks is to help keep the smaller (weaker) critters from eating your bait. They remember where the goodies are, the fermented Corn is just to draw them to the spot.
In the winter, it gets cold here, I use kitchen compost covered with straw. 50 kilograms of compost in a pile and covered (insulated) will generate its own heat. Fermenting corn will also generate it's own heat after you get it started. Much below 10 C and fermentation can slow way down.
Mostly guesswork more than my own experience, I've made my own booze, 30 grams of sugar and 15 grams of yeast for ten liters will cook up nicely in days when it is warm out. I'm not nearly that precise when cooking up Hog bait.
I cook mine up in 5-gallon batches (half Corn and half liquid), we all save the last inch in our Beer glass or bottle add a handful of sugar and add water as necessary and dump it into the brew.
In the winter Hogs get a craving for protein, nuts or meat, Rotting meat will get their attention. I've had good luck with Chicken scraps mixed in with a pile of fermenting compost. I had a poacher on my lease for a while, he used plastic buckets with rotting meat and fish hung in a bush 5-6 feet off the ground.
If you have a Vietnam store anywhere around you can try some Nuoc Mom, a fermented fish sauce that really stinks. I spray it on a bush, if the Hogs are anywhere around they will come to check it out. It is also a good cover for your scent. Don't spill any Nuoc Mom inside your car, it will smell like a Vietnam whore house for months.
When the Strawberries are ripe here the Hogs show up. I've thought about mixing in some powdered Strawberry drink mix into my Corn mash.
Good luck on your Hog hunt. The trick is to keep a constant food supply available (it really doesn't have to be a lot) they will visit the same spot most nights and often at around the same time, as long as they keep finding a little food there.