Forum listing display template for 3 deep
 

I'm trying to make my forums show 3 deep and it says I need a template if the display listing is anything greater than 2.
I've searched for a hint on how to do this in the manual but had no luck with my searches.
Can someone please tell me where I can find the info in the manual or tell me what kind of template I need to display forum listings 3 deep.
TIA