WebMail needs 2.0; - NOT compatible with current Portable Thunderbird 1,5

The main reason for my trying this thunderbird is that it is portable, and offers a quick way to get/send emails from various internet cafes. Unfortunately, current Webmail extension 1.3 can ONLY be installed with Thunderbird 2.0+. And the latest portable vers is 1.5. I searched for but could not find an earlier .xpi version of WebMail. But maybe someone could post here or somewhere an earlier webmail version which will work with the current Portable Thunderbird...? Otherwise, it seems to defeat the purpose of even using Thunderbird.