$ perldoc cpan |ack "[-][fiT]"
    -f  Force the specified action, when it normally would have failed. Use
        option, -i is not optional for installing a module when you need to
                % cpan -f -i Module::Foo
    -i  Install the specified modules.
    -T  Do not test modules. Simply install them.
            # install modules ( sole -i is optional )
            cpan -i Netscape::Booksmarks Business::ISBN
            # force install modules ( must use -i )
            cpan -fi CGI::Minimal URI
    Japheth Cleaver added the bits to allow a forced install (-f).