Basically a corpse/refuse stockpile that accepts everything that can reanimate (except skin which I tan) and anything else I wish to get rid of, like vermin corpses. It's set to accept bones from any creature that can grasp, to get rid of hand bones while keeping most of the useful bones. That was painful to set up. Next to the pile is a 2 z-level deep 3x3 hole surrounded by fortifications (with one opening). In the opening, I put a track stop, and set a haul route to take from the corpse stockpile, same items. Second floor is surrounded by fortifications, so that if anything happens to reanimate before burning, I can put a few bolts into it and give it another chance to burn. Third floor down is magma. Second floor is normally empty unless I need to put something down, to prevent magma mist related incidents.
Note that if you put the mine-cart and stockpile one level above the magma, large corpses will create magma mist, usually incinerating the dwarf which dumped the body. Also, I've had the a kea reanimate after being dumped, but before being incinerated. It flew out of the incinerator and upset my biohazard disposal teams.
And that's how I dispose of biohazardous waste without an atom smasher. Best part is that there's no micromanagement; everything is automatically incinerated, unless it revives before making it there.