Go to fair trade tobacco and look up kilning. Folks there have been experimenting with all phases of tobacco growing and processing. There are a couple of members of both this and that forum who are particularly adept with a crock pot.
I am probably going to get some details wrong here, but commercial tobacco is intentionally stored in big, crated, piles called bales in huge un-condidioned warehouses. The center of the bale warms up due to microbial and enzymatic activity, like a compost pile. This is fermentation. In cigar tobacco production especially, the bales are split up and re-stacked periodically so new leaves are always fermenting in the center of the pile.
This process can be replicated at home in any environment that can support hot humid conditions for weeks on end. The reason it isn't done commercially is because labor and storage time are way WAY cheaper than heating giant warehouses.
This is only done with raw leaf, by the way. You are free to experiment, of course, but I would think any finished, blended product would have added sugars or flavorings in it that would react differently to the process than you might want.