My uncle drilled holes in some of his and poured something inside the hole (forget what it was). As I recall, he said it would either hasten the deterioration from the inside... or that it was flammable and he was going to ignite it a day later and let the stump smolder underground.
For some reason, now that I type it out, I think it was more of the latter (smoldering) than rotting.
Perhaps he was going to soak with kerosene?
Anyways, that's all I know in it... I ended up popping them out with my backhoe and he never did it.
Richard