To generate textures only for the NPCs added by a specific mod, you may employ an undocumented method to generate the textures for specific NPCs. This process can take upwards of several hours, and is very redundant as most of this data has already been generated. This feature, however, is nearly useless for mod authors, because it will quite literally generate all NPCs from all loaded master files - including FalloutNV.esm. The base game solves this by generating NPC face textures for all NPCs in the game using Export NPC Face Textures, and then saving this data into the BSA. This results in severely uncanny mismatches between faces and bodies the faces will take on the colour specified by the mod author, but the rest of the body will use a default colour (usually Caucasian), which can result in very odd mismatches between face and body, especially when the actor is of a race with a significantly different base skin tone. In Fallout.ini under the section on the end user's PC, it can still occur that NPC textures will fail to generate - especially with ESPs rather than ESMs. Although this can usually be corrected by setting Newly added NPCs in Fallout 3 and Fallout: New Vegas will normally have mismatches between their body textures and their facial textures.

Export NPC Face Textures appears in the Character dropdown menu.

Fallout new vegas face texture