make sure to install rbappscript first. Then you'll need the MakeCustomShape action installed from here http://cl.ly/2x3Z2j3a2B0X292b1f1S. Theoretically that is it. Works for me, hopefully for you as well.

scriptingCSH.rb

require 'rubygems'
require 'appscript'    
                      
# Make sure to open your apps first. Appscript can get ahead of itself and not wait for them to load so it will fail
# Set your dir with AI files and thats it
dirname = "/Users/kenerickson/testCSH"   

ai = Appscript.app.by_id('com.adobe.illustrator')
ps = Appscript.app.by_id('com.adobe.photoshop')     
# ps = Appscript.app("/Applications/Adobe Photoshop CS3/Adobe Photoshop CS3.app")   

ps.activate()   
ps.settings.ruler_units.set(:pixel_units)          
ps.make(:new => :document, :with_properties => {
  :name => 'bookworm is a genius',
  :width => 800,
  :height => 600   
}
)     
       
Dir["#{dirname}/**/**"].each do | thisfile |    
  ai.open(MacTypes::Alias.path(thisfile))  
  layers = ai.current_document.layers.get    

  layers.each do |layer|     
    layer.has_selected_artwork.set(true) 
  end

  ai.copy()    
  ps.activate()  
  ps.paste()
  ps.do_action('MakeCustomShape', {:from => 'MakeCustomShape'})  
  ai.current_document.close(:saving => :no)
end 
ps.current_document.close(:saving => :no)