Could you make a scratching post for him out of similar fabric as that which covers your couch? Kittens do need something safe to scratch and a good post sounds like a possibility for you. Once you have one, put catnip on it and that should attract his attention. If you catch him scratching somewhere he shouldn't be, take him to the post and "help" him scratch there. The sticky tape is a great idea to discourage him from the sofa but he'll still need a place to scratch (part of cat nature )

NoahsMom's ideas about dealing with his aggression are right on.

Good luck to you. Please let us know how you make out.