The gens for DAZ characters are almost always separate objects that are loaded onto the character and usually you have to tell DS to do it by clicking on the 'Anatomy' tab and then selecting "Genesis # X Genitalia', where # is the version of the character and X is Male or Female. It's rare for venders to autoload a gen or build custom gens.
Most characters come without gens loaded and are smooth by default. However, many characters do have (at least some) pubic hair drawn into the torso mat by default, or at least stubble. You should be able to create a separate surface with the polys that have the stubble and overlay the color/texture of the surrounding torso or create a L.I.E. and place it on top of the area but DS isn't made to do this easily. You can use gimp, photoshop or even paint.net to alter the mats and import them back into DS in the runtime/textures/ folder of the character. Many tutorials on youtube on how to do this. I know you want to use DS to do it, but it's probably going to be clunky.