Get an SCT tuner with custom tunes for it, but i wouldn't bother with out doing all 6.0 supporting mods first. headstuds, EGR delete, being the minimum But I'd recommend a coolant filter, a bypass oil filter, and a new oil cooler as-well. I have a 2004 6.0l and its bone stock except for the exhaust but and I haven't had any trouble with it (minus an alternator but you cant blame that on the 6.0). But I wouldn't bother programming it with out the first 2 at least.
As far as an SCT dealer, there's a lot of good ones, just do some research on either dieselstop.com or thedieselgarage.com(seems slow anymore though) I was planning on getting one from elite diesel engineering or something like that but last I heard there customer service became horrible but I here River City diesel is pretty good.