Blender 2.79 (rendering 6 render layers)

So Im working on an animation using 2.79’s Internal render and I need to render 6 different render layers so that rendering the animation won’t be so slow (because as of now its taking hours to render one frame). I need to know what kind of node set up am I looking at to make this happen because I can’t seem to figure it out. I’ve tried Z passes, mix and add nodes and nothing gets the result i want. Can anyone help??