Use cpanminus to make installing / upgrading CPAN modules simple and possible in low-memory environments.
Install cpanminus:
curl -L http://cpanmin.us | perl - App::cpanminus
The application name is cpanm once installed.
Upgrade CPAN modules with cpanm
This will skip tests and display verbose output:
cpan-outdated -p | cpanm -n -v
Upgrade CPAN
cpan install CPAN reload cpan