The interview process for this job was very straight-forward. They don't ask questions that you wouldn't find with any "how to interview" google search. What any TCO interviewer is looking for is that you understand the chain of command, work well with people, but can basically get going on the work they need done. Also, they want to know that you are okay with basic or repetitive tasks.
I had two interviewers - both were very pleasant. They picked out some of my previous work (in the arts) and asked me about the change in direction with my career. So, be prepared to really talk about why you want to work in the public sector.
They then ran some office scenarios by me, such as asking questions on how I would prioritize my workload. Or, if I was working on a project that needed to be done by the end of the day, but was approached by a HEO with another project that they say requires urgent attention, how would I deal with that. They really just want a sense of how you will conduct yourself and how you work under pressure.