GTA:V collections of model (.ydd files) support have been added including import/export of skeletal rigged models. This allows an editing of player model, NPC and ped models at the first place, and opens wider range of editing possibilities for the game content (including minimap, buildings and accessory models).
Player model modding might require an additional rigging for proper model behavior, so a replacement model can wink and talk properly. Additionally, you might need to do a texture work, as cloth and face wrinkles require a set of bump-maps. Cloth might use up to four displacement bump-layers for walking phases, and face can use up to six bump-layers for different emotions. You can explore (and even utilize on your own models) original game textures for this purpose. On the other hand, you can use generic ped shaders with no need to care of these extra features if you like the look of the model you create.