I am testing installing modules we use in /usr/lib/perl5/site_perl/5.8.8 and leaving everything in /usr/lib/perl5/5.8.8 unchanged. This test looks good to me.

cpan> get  PHRED/Apache-DBI-1.10.tar.gz
[...]
cpan> make  PHRED/Apache-DBI-1.10.tar.gz
[...]
cpan> test  PHRED/Apache-DBI-1.10.tar.gz
[...]
cpan> install  PHRED/Apache-DBI-1.10.tar.gz
[...]
Installing /usr/lib/perl5/site_perl/5.8.8/Apache/AuthDBI.pm
Installing /usr/lib/perl5/site_perl/5.8.8/Apache/DBI.pm
Installing /usr/share/man/man3/Apache::DBI.3pm
Installing /usr/share/man/man3/Apache::AuthDBI.3pm
Appending installation info to /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/perllocal.pod
  PHRED/Apache-DBI-1.10.tar.gz
  /usr/bin/make install INSTALLDIRS=site -- OK