Replacing the blend door actuator really isn't a difficult job, and contrary to popular belief, one does not need to "rip" out the entire dash to get to it. On a scale of 1-10 its about a 5. It requires the center console to be removed, the dash to be unbolted from the firewall, and then pulled away on the passenger side enough to access the actuator. Yeah, a lot of fasteners and parts need to be removed but it can be done in under 4 hours if properly equipped. In order to keep all the nuts, bolts, screws, and other misc. hardware organized I use a bunch of sandwich bags categorizing and labeling them as I go. Remember that you'll be playing with an airbag so you'll want to disconnect the battery before you start the job.
The biggest and best suggestion I can make to anyone doing their own work on their SHO, is to go to their local Ford dealer and order the service manual for their year car. Much like a set of wrenches or sockets, it's an invaluable tool that will more than pay for itself over time.