Hi,
first off, do you have the navigation system or not? It will make a difference in the instructions you need.
The easiest thing to do is go to the main Toyota website and click on the Letstalk.com link (Bluetooth hyperlink). This link is for the phones that have been tested and work well for specific vehicles. You may be able to link, but not access all functions, for example, so use the Letstalk site for complete details.
The weblink is
http://wsf1.toyota.letstalk.com/bran...ta-bt/home.htm
On letstalk.com you can get full instructions on how to pair your Treo with the Sequoia, select if you have navi or not.
More importantly, there will be that list of what functions will work with the 2008 Sequoia and which will not.
You may be able to link the Treo, but not download the phonebook in one dump, for example. The list of functions you get after entering your info at the link above will tell you.
Plus, you can print the instructions once you have the info pulled up.
Good luck.