The buckle/strap suspension is definitely the best configuration to order from Warbonnet. I often switch it out, but it's just so all my gathered-end hammocks are set up the same way. The stock setup is nice.
It's a small continuous loop larks-headed around the gathered ends and splied onto the two triangle buckles. Long straps are then threaded through the two buckles. You can then wrap the strap around the tree and use a carabiner or dutch clip to hold the strap onto the tree.
Brandon has a pretty decent setup video that shows how the suspension works - and some good tips on setting up the Blackbird, here:
http://warbonnetoutdoors.com/setup.php