You need to look for the internet sales manager either through email listing or simply by calling up the dealership and asking for him/her directly. This person deals strictly on volume.
In my case I pretty much had in my mind what I wanted and made that one call to a referred contact which immediately netted me a price of $500 over invoice.
Keep in mind, when you are ordering, you'd have some leeway in reconfiguring your order (color, options, trim) right until before your slot reaches 150 (production) status. I am sure that posters here would attest to themselves barraging their respective CAs with order detail changes right until the last possible minute.