No - there has not been any more than what you have already found on the actual interview process that I remember from this forum. Did you check the other forum link that was found in the older threads?
Congrats on the interview! I have had my ear to the ground on that job as well in the past. I'd be very interested to hear what you have to say about the process and any other information that you may care to share after your interview.
Of note - many moons ago - I actually did have a job interview to be a Deputy US Marshal. Before the interview date came I was selected for OCS and never actually went through with the interview. I wish I had.