Here's an idea (dunno how portable she be):

BEGIN {
     die "You must use 5.004 or 5.6.0 to run this script.\n"
       unless ( ($] >= 5.004 && $] <= 5.005) || 
                ($] >= 5.006 && $] < 5.006001) 
              );
}
[download]

I think that'll work, anyway =)

perl -e 'print "How sweet does a rose smell? "; chomp ($n = <STDIN>); 
+$rose = "smells sweet to degree $n"; *other_name = *rose; print "$oth
+er_name\n"'
[download]