im sure you got plenty of good answers on here. what we try to do is Tell them NO, thats bad in a stern voice, and if they keep doing it, try to ignore it. the more you give in to it and say no, the more attention they get and they keep doig it.
Maybe try time out instead of losing tv time so the punishment is more quick to take affect? I dunno. Definitely be consistant with punishing and explaining to him that its not nice at all.
try to get out of the habit of cursing