actually, on mine it's done entirely differently. When I try to log into verizon BIS online it tells me to access BIS from my handheld.
Sooooo.. the way to do it is go into the Setup folder, then to Email Settings, click on each individual email account you have set up, and scroll down and do it that way.
I guess for VZW Tour owners at least you can't access BIS via the web. It's all done through the handheld, and specifically through Setup > Email Settings. You can't get to it through Messages > Options > Email Settings.