Yes, you can. Go into the AiCarriers folder and adjust one of the .cfg files. I seem to remember having trouble modding the aicarriers.cfg, but I've adjusted the xpack.cfg file with no issues.
The "title=" is how it will display in the Aicarriers menu in the sim. The "unit.X=" just needs to have the ships title, from the ship's .cfg file. The numerical values are the distance from the center of the formation, or zeros if it's only one ship.
Some ships don't seem to work well and just sink immediately. If that's the case, make a new folder, copying the model and textures, copy the ship.cfg file from one of the default ships, and give it a new title.
[formation.2]
title=USCG Cutter (Aerosoft)
unit.0=VEH_Aerosoft_CGCutter, 0, 0
[formation.3]
title=Hamagiri
unit.0=AI_HAMAGIRI, 0, 0