I'd recommend EZskin2 for this task. Load V4 and the prop. Select the prop, go to the edit tab, select the material you want to edit, select a material from the drop down menu and apply. Skin or innermouth, since the labia minora are partly covered by mucosa. If it still does not blend in, i would get rid of the texture map and use a part of the orignial skin map your'e using.

edit: No need to get giggly, it's just genitals, isn't it?