Ralph, yes this is definitely possible. A couple of things to note: Tableau say this is unsupported, but they then go on to give detailed instructions on how to make your own palettes. This document sort of implies that diverging only uses two colors, but you can actually use as many colors as you want. Somewhere I found a Preferences file someone created (sorry I can't remember who) that has several dozen palettes with lots of diverging and sequential colors:
I edited this one (put the dark band in the middle) just to confirm how it was working. On this one the author was running through 11 colors. I've attached the original file. Just unzip it, rename it Preferences.tps and put it in your Tableau Repository folder.
EDIT: Found it! Michael W Cristiani produced the attached file and gives a detailed description of several different resources available for creating custom palettes. Thanks Michael! Great stuff.
Message was edited by: DataViz Dude
This is really great. Thanks for the tip!
Ralph, you're welcome. Note that I found the source of the file and updated my post. Do visit that link to Michael's post, he's put a lot of useful links there.