my $record_end = qq{\$\$\$\$\n};
while (<DATA>) {
    next if ( $_ ne $record_end );
    print "--CSV stuff--\n";
}
continue {
    print;
}

__DATA__
example 1
example 2
END
$$$$
example 3
example 4
END
$$$$

##</code><code>##

example 1
example 2
END
--CSV stuff--
$$$$
example 3
example 4
END
--CSV stuff--
$$$$