C:\_32\pscrpt>type Config_m.pm package Config_m; use warnings; use Config; my $tied = tied %Config; $tied->{installsitebin} = '/usr/bin'; 1; C:\_32\pscrpt>perl -V:installsitebin installsitebin='c:\MinGW\perl512\bin'; C:\_32\pscrpt>set PERL5OPT=-MConfig_m C:\_32\pscrpt>perl -V:installsitebin installsitebin='/usr/bin'; C:\_32\pscrpt>