Knowing this will probably happen again i would make a script called /usr/bin/perlcron

#!/bin/sh
perl -I /some/special/libpath:/another/special/libpath "$@"
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and chmod ugo+x it. Then when you enter your command to be run by cron just preface it with /usr/bin/perlcron. ie "/usr/bin/perlcron myscript". This has the advantage that you can also do things like setup a special path when your path is not the path that cron uses. That way you dont need to add any special code to your scripts, it is taken care of in perlcron. And the next time you want to run a perl script by cron you are all set to go,, just use perlcron again to start it