... write a program to change them for you?
#! /usr/bin/env perl
use common::sense;
use Tie::File;
tie my @f, 'Tie::File', shift or die $!;
if ($f[0] =~ m,#! */usr/bin/perl( -w)?,) {
$f[0] = '#! /usr/bin/env perl';
splice @f, 1, 0, 'use warnings;' if $1
}
untie @f;
Somethin' like.