I dont know if it was luck, or if this is the way it is, but I just did this 2 times, and the person that was leading the group knew exactly where to go.
pt set up: 75nin/dnc, 75sam/thf, 66sam/thf (me). We went in as uncapped.
We needed to sub thf to gain access to Cyclone with our daggers.
We started with the north room. My Cyclone as a 66 Sam was enough to wipe out the chigoes. This had an NPC.
The second room was in the middle, and this one had Ryaaf.
Our 3rd Room was on the east side, and this contained the 3rd NPC, which completed our mission.
In the 2 runs that we did, they were the same NPCs in the same place. If this is truely consistant for all runs, then this is by far the easiest Assault so far.