You can do this by assigning different materials to different faces, and also with UV mapping.
With UV, you make the whole object one texture(can be done differently but this is the standard) and then upon exporting to photoshop or whatever, you paint things in where you want them to go. So you paint in a nipple where the nipple is, ect.
What I think your talking about, is assigning multiple materials to an object.
To do this, select the faces you want for a certain material and press “new” under the “mat:” bar in the edit buttons.
Then with the faces selected, press assign.
Create as many new materials as you need, and assign each set of vertex’s to it until your whole object is put together.