Tweaky, 12 string STs and TLs are available as a custom option. I am currently (and very slowly) building a 12 string ST kit that Adam got for me. I think from memory it was $50 over standard price, but I ordered it over a year ago and the pricing structure has changed a bit this year.

My very out-of-date build thread is below.
http://www.buildyourownguitar.com.au...ead.php?t=3842