Originally Posted by tight-wad
Use a strong biner on the end of the support rope, leave the webbing in the buckles. Loop the support rope with the biner around the tree as many times as necessary to take up the slack. Clip the biner, adjust at the ring as necessary. To undo, just unclip the biner, and roll it all up into your preferred snakeskin, bishop bag, ... Really easy.
I should have said support "webbing" not rope...