I found it under Account Details > Return. There's an "overall passback parameters" section at the bottom of that page, where you can enter the password.

As I understand, this means the transaction goes straight back to gmail, rather than having an intermediary confirmation screen at 2checkout.

I tried a test payment. 2checkout sends me to a gmail page which then refreshes. However, when it refreshes I get a "page cannot be found" error. The URL it is trying to reach is
https://www.2checkout.com/cgi-bin/sbuyers/webmail.cgi?t=brewt

Any ideas? Is this a bug in the gmail code? I think I have all the settings entered correctly, but I'm not being passed back to a page that exists.

Jason