As I'm sure you realise 'Huckleberry Finn' is written in the accent and idiom of the American Deep South, in the 19th century. In correct modern English the sentence would read 'People would come from miles to hear Jim talk about it.'The verb 'come' is intransitive and therefore cannot have a direct object. 'Miles' is indirect and therefore needs a preposition of some kind, clearly 'from'. The principal verb is 'would come' used in the imperfect tense i.e. meaning 'people used to come from miles....'The subject is 'People', and the other indirect object is the clause 'to hear Jim talk about it'. 'Tell' is transitive and would require a direct object within the clause. You can 'tell a story about it', or 'tell a stranger about it', but you can not simply 'tell about it'. 'Talk' is intransitive so for correctness Jim needs to 'talk about it'.
Transitive verbs must always have a direct object. The most frequently recurring mistake in modern English is when people are urged to 'Enjoy', as an imperative but with no object. You cannot simply 'Enjoy' any more than you can simply 'love' or simply 'abuse'. You have to enjoy something. So next time the waiter or waitress puts a plate in front of you and urges you to 'Enjoy', tell him or her that it is a transitive verb and requires a direct object.