Yes you can have as many versions of Perl as you like. Say you wish to retain your current perl which will have either a binary or a link in /usr/bin/perl (this is a good idea as installing a new perl should not break anything old). First install the new perl somewhere (say 5.8.8), then create a symlink.

$ ln -s /usr/local/new_perl5.8.8_dir/bin/perl /usr/bin/perl588

Then you just need to do

#!/usr/bin/perl588

to use it in a script and

$ perl588 Makefile.PL
or
$ perl588 -MCPAN -e 'shell'

to install modules into that new Perl.
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