Until someone shares or creates the mod to use the WA state API, patternman posted a great alternative in this thread:

http://www.zen-cart.com/forum/showth...180#post908180

I added to that by making all 60k+ local tax records available to import directly to your tax_rates_local table.

To download the files click here:
http://www.gemni-gems.com/sql.zip

For the other options to this process, refer to page 34 of the thread posted above.

Good luck all! And if anyone has a better, faster way, please share.