I recently installed CBBE, Body Slider & Outfit Studio and COCO Body (3BBB) SE. (I'm running AE)
I was able to build the [COCO] CBBE_Vagina_03 body in BodySlider, and I set the labia slider settings to 100 on both bars.
Here is a screenshot of the result.
The labia did become more noticeable after this build, so I'm pretty confident Body Slider is setup correctly, but what I am hoping to be able to customize the labia to look more like this model