Scott,
After doing some research on the difficulties of fooling with the color of wools, I settled on trying RIT color remover (see here
http://www.walgreens.com/store/produ...=0&id=prod3817) and it worked like a charm. It didn't take long, either: just a minute or two of stirring the hose in a solution of the color remover and hot water. Don't confuse RIT color remover with the RIT whitener, though, as the later is effectively a full bleaching. The purpose of the color remover is exactly ours: to lighten the color. The one caution I would add was that the color also drifted a bit, and ended up with something that was more yellowish than I expected, but fortuitiously so. I have no idea what kind of color changes might happen with blues or reds.
Good luck if you try it.
Cirthalion