$ perlbrew switch perl-5.20.2t
$ perlbrew list
  ...
  perl-5.20.0t
* perl-5.20.2t
  perl-5.22.0t
  ...
$ which perl
/Users/ken/perl5/perlbrew/perls/perl-5.20.2t/bin/perl
$ perl -v | head -2 | tail -1
This is perl 5, version 20, subversion 2 (v5.20.2) built for darwin-thread-multi-2level