Yellow: Approximate Williams topo line
Green: Approximate Swain topo line
Red & Blue follow Williams description. Only those variations stay at 5.5, if you follow the yellow line directly you will encounter climbing that may be mentioned by Swain as a 5.7+ variation.
Using the picture below you should be able to locate the start of the route. It follows a fairly distinct corner and passes some old pins. I think it's cool to do for historical reasons, but otherwise it's not a very appealing Millbrook climb.