I don't have the book with me, so I am not sure what you are referring to. Maybe if you can provide some key phrase, we can see/preview the page on Amazon with their search inside feature.
My first thought from your description is to use a parameter to allow the use to select what to sort by, and then a calculated field that only returns values with the dimension matches the parameter and use that calc field to sort the dimension.
The book is at Amazon at http://www.amazon.com/Now-You-See-Visualization-Quantitative/dp/0970601980/ref=sr_1_1?ie=UTF8&qid=1301948603&sr=8-1. Click "Look Inside" and search for "link multiple graphs" and select page 62 from the results. There is a visual example in the middle of the page and the author's suggestion is in the 3rd bullet at the very bottom of the page.
I started a related thread this morning that would provide a different way of solving this issue. See http://www.tableausoftware.com/support/forum/topic/suppressing-sort-while-retaining-filtering-server-views.