According to the module's page on Kobes' repository (try [kobes://Win32::IE::Mechanize] on this site, it produces the link Win32::IE::Mechanize), bottom of the page, the PPM module is only available from their repositories, both for perl 5.8.x and for perl 5.10.

You'd better add the appropriate repository to your PPM, and then try to install it. Follow the instructions on the site if on an older perl; but in the newest editions of PPM (the GUI version), it's just a matter of choosing to add a repository you want to add from a dropdown. Which is very nice.