I didn't know what Inquisimunda was, so I looked it up and found the website. Here it is the link for the rest of you who don't know what it is: Empire of Ghosts: Inquisimunda
Xhmm...there are a few types of teams I could think of right off the top of my head.
1). A Tau Water caste merchant and his entourage doing business in the hive city
2). Fire warrior escort (of a Water caste merchant) performing a separate mission
3). Fire caste mercenaries - either the dodgy Tau of N'dras or the rebellious Tau of the Enclaves
4). All Kroot mercenary team. Kroot fought as mercenaries long before they met the Tau (and still do)
I have a couple more, but I'd have to write you up some special rules for you.
5). Swagmen of N'dras - Tau equivalent of Ork Freebootaz and Lootas but with the Greater Good!
6). Covert Operations Team (Tau Empire or Enclaves) Specially trained team of water caste operatives on a covert mission. Think: James Bond
or Bourne Identity
Water caste merchant. In Imperial China there was no diplomatic corp, instead all merchants who wanted to trade with foreigners had to get a special license from the Emperor. This license made them in effect, agents of the Imperial throne; or in other words diplomats. Any trade deal with Chinese merchant was also a treaty with the Emperor of China. It was meant that Chinese merchants were intelligence service of the Empire, as they had to send monthly reports on the situation with the "barbarians". The similar concept would work for Water caste merchants trading outside the Tau Empire. And you can see the parallels with the Imperium's Rogue Trader Captains.
A Water caste merchant's entourage could be anything from the Tau fire caste: standard fire warriors, pathfinders, stealth suits (X-15), Kroot, Vespid, Gue'vesa soldiers etc. Even human or Eldar mercenaries could be part of the entourage.
A Tau mercenary army could be any mix of units from a standard Tau army list. Though I can't image more than one Crisis Battlesuit. Kroot and Vespid as well.
TauManMission Impossible Theme