NIVLACART'S PROFILE

author=Trihan

Audio.se_play("Audio/SE/filename")

You can supply volume and pitch as optional parameters after the filename.

Edit: Or are you looking for where in the scripts to put that?

author=karins_soulkeeper
Yeah, it is (and not very difficult too). Here's the draw_face method that's responsible for it:

class Window_Base < Window
  def draw_face(face_name, face_index, x, y, enabled = true)
    bitmap = Cache.face(face_name) # default
    #bitmap = Cache.pictures(face_name) # if you want to use pictures, use this instead 

    rect = Rect.new(face_index % 4 * 96, face_index / 4 * 96, 96, 96)
    #^^ to change the size of each face, alter the values in this line ^^
    # example, to use 1280 x 720 px faces, you use this line:
    #   rect = Rect.new(face_index % 4 * 720, face_index / 4 * 1280, 720, 1280)

    # though this would still require your images to be formatted like the
    # default face sets.
    # to use just a single image (and not the usual 4x2 format), use this:
    #   rect = Rect.new(0, 0, image_width, image_height)

    contents.blt(x, y, bitmap, rect, enabled ? 255 : translucent_alpha)
    bitmap.dispose
  end
end

This'll affect all faces show in the game though...