The simple solution is to use this module I just whipped up (SelfRecord.pm):

package SelfRecord;
use strict;

open SELF, '>>', $0 or warn("huh?: $!");
select SELF; $|=1;
print "\n__END__\n";

1;
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This is used simply, so that:

#!/usr/bin/perl -w
use strict;
require SelfRecord;

print "Hello!"
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Becomes:

#!/usr/bin/perl -w
use strict;
require SelfRecord;

print "Hello!"

__END__
Hello!
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When run.