It's been too long since I did Dark Waters or OM, but you would most likely be most interested in Karamazovnew's KiUB add-in mod, which is in the MODS folder after the Dark Waters activation (?? maybe ??). You could look in the mod itself, and see if there is a pdf or ReadMe file in there... Karamazovnew had a separate mod download
KiUB Kriegsmarine Interface for UBm for a time, and had a link to his documentation, but those were on filefront, which is now defunct, but you might be able to find something in the Downloads section here on SubSim, or perhaps someone has a better memory than mine and can link you.