Install it in your home area.

CPAN can do that.

I have this in my cpan config file (~/.cpan/CPAN/MyConfig.pm)
'makepl_arg' => qPREFIX=~/myperl LIB=~/myperl/lib INSTALLMAN1DIR=~/myperl/man/man1 INSTALLMAN3DIR=~/myperl/man/man3
Then:
perl -MCPAN -e shell
Followed by 'install Devel::Cover' will do it.
Or it you have the Devel::Cover tar ball do this
LIB=/home/jjm/myperl/lib perl Makefile.PL