I ordered mine out of AZ and it got ordered with the CA emmisions package. To register it, and when you accept the truck you specify it is for CA w/ the dealer and have him acknowledge that, so he accepts responsibility, and have him point out the emmissions sticker on the valve cover. It will have a line on it specifying CA legal. The DMV WILL inspect, and look for that. I also noticed a special line on the cert of origin that also said CA legal.
To order it, it used to have to be a border state, and it still may, but if you are picking a truck out of stock, some dealers are getting fleet orders that are CA legal... but you HAVE to have that sticker on the valve cover, or you go to jail and don't pass GO when you try to register it.
There was a thread about this about 6 months ago that included a jpeg attatchment that had a picture of the valve cover sticker on it. The thread was comprehensive on the topic. It involved a truck purchase out of Vegas that wasn't legal, and the guy was hosed. Any questions, holler.
sarj