There is an ongoing outage on the primary CPAN mirror. It is possible to work around the issue by using MetaCPAN as a mirror.
To install KSx::Highlight::Summarizer, copy and paste the appropriate command in to your terminal.
cpanm
cpanm KSx::Highlight::Summarizer
CPAN shell
perl -MCPAN -e shell install KSx::Highlight::Summarizer
For more information on module installation, please visit the detailed CPAN module installation guide.