@lunarea -- He specifically asked how to do it with a script
<actor>.set_graphic(character, character hue, battler, battler hue)
where actor is a Game_Actor (the hero's sprite is the first party member, $game_party.actors[0])
character is the name of the character_set you want
character hue is the hue displacement (0-360)
battler is the name of the battler graphic you want
battler hue is the hue displacement (0-360)