Kill the crabs by stabbing them just behind the eyes with the point of a sharp kitchen knife. Rub the cut lime over the crabs to thoroughly clean them. Rinse the crabs under cold running water. Remove the claws and set aside. Now remove the shells from the body of the crabs and set them aside. Cut each of the bodies in half so that each half has legs attached. Set body parts aside. Using your fingers separate and discard the digestive bags from each crab shell, and set aside the crab shells with any of their remaining juices.
To assemble the matete, in a large Dutch oven or heavy-bottomed saucepan, heat the oil over a medium heat, and add the roucou oil. Lightly fry the smoked ham hock for about 5 minutes, just to quickly seal and color the outside. Remove the meat and set aside. To the remaining hot oil, add the scallions, garlic, the claws, and the crab bodies. Scoop the contents of each shell, including crab juices, into the saucepan (this is what permeates the dish with that wonderful crab taste).
Discard the crab shells and add the parsley, celery leaves, water, thyme, chile, bay leaves, and the fried smoked ham hock. Stir the mixture, taking care not to crush the chile. Taste and adjust the seasoning with salt and pepper. Bring to a boil and add the rice. Stir again to mix. Lower the heat and cover. Simmer slowly until the rice is soft and cooked and all the liquid is absorbed, about 20 minutes. Remove the chile. To serve, arrange the matete on a large serving platter, taking care to display some crab throughout. Serve hot.