You can get these low temp using a cold smoke adapter and a PID controller. Or just The pid and leaving the smoke generator off.
You can start your process at the 120 F and it will be just fine. He actually got that recipe from this site.
A PID controller is use to controll your element with more precision than the regular smoker temperature controller. Instead of plugging the cord for the element into the smoke generator, you plug it into your PID. Check there http://www.auberins.com/index.php?main_page=product_info&cPath=14_28&products_id=151