1. Make a loop at the end of your cord. This could be an eye-splice, in the photos it is a bowline on Vectrus whose end has been finished with a bury (btw, a very nice way to finish the ends of these weaved cords!)
2. Pass the loop through the lightweight black loop sewn to the bugnet (I think).
3. Bring the working end of the suspension cord around the whipped hammock end, and pass through the loop in the suspension.
4. Finally, bring the working end of the suspension cord through the ridgeline loop that sticks out of the whipped hammock end.
That's all there is to it. So don't be afraid to work the stock suspension apart and put your whoopie sling on. It's a very easy mod.