perl -MCPAN -e shell

cpan shell -- CPAN exploration and modules installation (v1.9205)
ReadLine support enabled

cpan[1]> o conf yaml_module YAML::Syck
    yaml_module        [YAML::Syck]
Please use 'o conf commit' to make the config permanent!

cpan[2]> o conf commit
commit: wrote 'C:\usr\lib/CPAN/Config.pm'

cpan[3]>