Changing the spoke is simple. The only trick is the threads are left-handed. That makes the spoke wrench turn the same direction as wheels with conventional nipples with right hand threads. If this wasn't done, it would drive a wheel builder crazy.
The problem is that you may have bent the rim in the crash and using excessive spoke tension to correct that problem is not going to result in a long-lived wheel.
I had to replace one spoke on my rear Ksyrium. After I took the cassette off, it was a 5 minute job.