Someone once said games are a series of interesting choices - so here's how to make a few more:

Have a poke around the ol' internet for some basic modding guides for the Total War series. Here's two to get started:

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=1694945483

https://twcenter.net/threads/sebidees-complete-guide-to-warhammer-unit-modding.749888/

Download and set up Rusted Pack File Manager (RPFM) per whatever guide you are using.


Once the tools are set up you need to find where the mod is located, another quick google search might help but for me mods are in a series of folders here:

C:\Program Files (x86)\Steam\steamapps\workshop\content\

Search through the folders to find the correct game folder, then within that for the right mod folder. Lost and the damned 3 is called: !C2_public_lost_3.pack

Open it up when you find it.

A really good place to start poking around would be the 'main_units' & 'land_units' tables as they govern a whole bunch of basic stats like how big the unit is, what its armor & weapons are etc

I anticipate most people looking to customise the mod will be picking and choosing which units they actually want so lets look at recruitment in detail. It might be useful to think of recruitment as being governed by two basic things: Permission (who can recruit what) and Method (how is it being recruited).

Permission:
• units_to_exclusive_faction_permissions_tables - if a unit is only meant to be used by a certain faction put it here - OR - remove it from here to be used by many
  
• units_to_groupings_military_permissions_tables - if a unit belongs to a whole bunch of factions (a 'military group') put it here. MOST generic units go here.

Method:
• building_units_allowed_tables - the vast majority of units are assigned to be recruited from buildings and this table governs that
  
• scripting & other indirect stuff - I know nothing of this unfortunately

A general rule of modding is to be careful of what you change so rather than delete the units in their entirety you can simply block access to them by removing either the method of recruitment or a factions permission to recruit.

Units also appear in garrisons, rebel armies and custom battles. You can change what appears where in the following tables:

• various "armed_citizenry" tables - which units are assigned to which garrisons
  
• faction_rebellion_units_junctions - controls units spawning into rebel armies
  
• units_custom_battle_permissions - controls units appearing in custom battles

EXAMPLES:

1) I want cultists to appear in rebel armies & settlements but not main enemy armies - disable army recruitment via removing cultist units from the building_units_allowed table to stop direct recruitment
2) I want to completely disable a unit from appearing at all - probably enough to remove it from the military_permissions & faction_permissions tables but you could scrub it completely by checking the armed_citizenry and rebellion tables as well


A useful tip when modding is to have 2 instances of RPFM running at the same time: One with the mod .pack you are changing and a second with the TW3 main data.pack file open so you can quickly switch between the two and cross-reference data. This is not strictly necessary anymore since RPFM has multiple tabs these days but it still might be useful for some folks.

Make sure when you have saved your changes you save a NEW VERSION of the mod directly into the TW3 DATA folder alongside all the official .pack files and DO NOT OVERWRITE the original mod in its workshop folder.

There's nothing wrong with saving-over the original mod in its folder except that the steam workshop will SAVE-OVER your save-over whenever it detects the need to do so - I.E. when I update the public mod all your CHANGES WILL BE LOST unless you are running a separate/private version.

If all this seems like too much hassle then download the excellent console mod and spawn units directly into the game in seconds:

https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2791241084&searchtext=console

Here are the unit keys:

latd_chs_cultmob
latd_chs_cultbow
latd_chs_cultzeal

latd_cst_deck_halb
latd_cst_handgun
latd_cst_swash
latd_cst_knights
latd_cst_norse
latd_cst_blackwind
latd_cst_grog
latd_cst_ogre

latd_tmb_numas_spear
latd_tmb_numas_scout
latd_tmb_numas_cav

latd_vmp_sword
latd_vmp_spear
latd_vmp_halb
latd_vmp_xbow
latd_vmp_handgun
latd_vmp_canon
latd_vmp_mortar
latd_vmp_cav
latd_vmp_knight
latd_vmp_thrall
latd_vmp_thrall_2h
latd_vmp_thrall_cav
latd_vmp_vassal_spear
latd_vmp_vassal_bows