http://www.jwz.org/blog/2012/11/applescript-2/

itunes-mk-playlist.rb

#!/usr/bin/env ruby
# encoding: UTF-8

require 'appscript'
require 'pathname'
include Appscript

### Usage:
# ./itunes-mk-playlist.rb                                                                                            \
#   ~/"Music/iTunes/iTunes Media/Music/Atomine Elektrine/Zektor X/09 ...and Ever.mp3"                                \
#   ~/"Music/iTunes/iTunes Media/Music/DarkDriveClinic/Noise in My Head/09 Angel of Malcontent.m4a"                  \
#   ~/"Music/iTunes/iTunes Media/Music/Rome/Die Aesthetik Der Herrschaftsfreiheit - Band 1/02 The Angry Brigade.mp3" \
#   ~/"Music/iTunes/iTunes Media/Music/The Submarines/Love Notes_Letter Bombs/10 Anymore.mp3"

paths    = ARGV.map { |s| Pathname.new(s).realpath.to_s }
itunes   = app('iTunes')
name     = "jwz-#{Time.now.strftime("%Y-%m-%d %H:%M")}"
playlist = itunes.make(:new => :user_playlist, :with_properties => {:name => name})
library  = itunes.tracks.get.inject({}) { |h, t| h[t.location.get.to_s] = t; h }
tracks   = paths.map { |path| library[path] }.compact
tracks.each { |track| itunes.duplicate(track, :to => playlist) }

You'll want to gem install rb-appscript first.