Best way to install local module is to install module “local::lib”.
CPAN Local::lib
But you can also manually do it.

First export your username

 export username=ketan

create the .cpan directories

 mkdir $HOME/.cpan/
 mkdir $HOME/.cpan/CPAN/
 # This is so it ignores the global CPAN config
 
 echo "\$CPAN::Config->{cpan_home}='/home/$username/.cpan';" > /home/$username/.cpan/CPAN/MyConfig.pm

Then Execute a CPAN shell

 perl -MCPAN -e shell
OR
 cpan

Then when in the shell type:

 o conf init

to reconfigure CPAN, replace all \*/root/.cpan/\* with /home/$username/.cpan/*

Then edit /home/$username/.cpan/CPAN/MyConfig.pm and change the makepl_arg so that it has your PREFIX line as well:

 'makepl_arg' => q[INSTALLDIRS=site PREFIX=/home/$username/perl/],

Finally the env variable PERL5LIB needs to point to the new module installation paths:

 export PERL5LIB="/home/$user/perl/share/perl/5.8.4/:/home/$user/perl/lib/perl/5.8.4/";

and then you should be able to use CPAN to install modules.

I then modified the Oddmuse script so that the new module install directory was in @INC so that Oddmuse could pick up the modules. Put the following line somewhere near the top

 push @INC,qw(/home/$user/perl/share/perl/5.8.4/ /home/$user/perl/lib/perl/5.8.4/);