I cut down and debarked som TOH and rendered it into charcoal. I used a metal coffee can with a double thickness of tinfoil on top wired closed. I poked a small hole in the foil and it gassed off for quite a while. I lit the gas coming out and it burned vigorously.
I simply put the can in the fire pit and stacked "fat lighter" around it and it burned until it stopped gassing off. I retrieved it the next day and the charcoal was perfect.