Where I work, there is a "transparent proxy". Basically that means that the router between the internal network and the Internet has a rule that diverts outgoing connection attempts to an authorization server. When a site is visited with a web browser, the browser can authenticate to the authorization server, which then sends a new rule to the router, allowing the associated internal IP address to make outbound connections.

Once that is done, other programs on that PC can make connections until the rule expires.

If your company's proxy works the same way, then visiting www.cpan.org should make it possible for the cpan command to install a few modules. When it fails, use the browser, again, then retry the cpan command.