your getting a new alternator, that means it should have a pulley on it , so just undo the belt tension then take the whole alt. off, if you need to take the pulley off just do it while its off the car then swap the pulley on the new one, but i dont think youde have to. best way to use a impact wrench, then wrap a towel around the pulley and have someone hold it then hit it with the wrench... if you aint got air tools try a breaker bar or a rachet while someone hold the pulley