Took me a few days to locate this. Sorry, it's not a link, but a pattern in: "The Creative Pattern Book" by Judy Martin. On page 100 she shows a quilt "Horn of Plenty", which is basically a Thousand Pyramids quilt, with subtle value shifts from light to dark. Her triangle sorting process sounds very similar to what you describe. You can get a used copy for less than $1 + postage:
http://www.amazon.com/Creative-Patte...e+pattern+book
This quilt is on my bucket list!