The spec tire actually help the class at my track. People were having troubke with the old x patterns. Now the usgt class is only about a second behind 17.5 for lap times.
As for softening them up. The local guys have just been ueing SXT 3.0 like always. It just takes a few runs to break them in. It also helps that at the end of the race day, you clean your tires then coat them in traction compund and put them in a ziplock bag so they dont dry out. I am sure there are lots of other ways, but thats what I do.