Supondo que o homebrew esteja instalado, primeiro faça:
brew install readline
cpan Term::ReadLine
cpan
Agora vem a parte complicada. Dentro do shell cpan:
look Term::ReadLine::Gnu
perl Makefile.PL --includedir=$(brew info readline|egrep '[[:digit:]]+ files,'|awk '{print $1}')/include/ --libdir=$(brew info readline|egrep '[[:digit:]]+ files,'|awk '{print $1}')/lib/
make install
^D # to quit sub-shell
quit
Feito.
Eu sugiro usar o perlbrew também.