I applied to the DOJ SLIP (DOJ made me apply to SLIP as a 3L because of my Joint Tax LLM) before I knew I had an offer from my summer firm, so Honors may be a bit different. I also applied to a few other agency Honors programs.
I had a phone interview. It was surprisingly laid back- very much like the firm interview with the standard resume quiz. However, I never really heard from them after that. AFIK they did not contact references, but I think that only happens immediately pre-offer as a background check type of thing.
I also had an on-campus interview with the IRS Honors program. It was also very much like your standard firm interview, although they were definitely just reading a list of questions.
The unifying factor seems to be that you get an interview and then hear nothing. Most people don't seem to ever get rejection letters.
Sorry to say it though, if you applying this year and haven't gotten an interview offer yet, you probably aren't in the running anymore.