You don't need a local shop, tunes are sent thru email. Pick a tune writer, contact them or fill out the form on the website. Sit back and wait for your tunes, try them out, and if you have anything you want the tune writer to change to your liking, then have them revise the tune.
Here are the popular SCT tune writers in no particular order.
Powerstroke Diesel Tuning | Gearhead Automotive Performance
Welcome to Quick Tricks! Custom Tuners Miami, Florida
6.0 Liter Tuners
There is also DP-tuners and Truck Sorce Diesel.
Here is a thread with more info.
list of tunes and where to get them?