can´t change size of INPUT field from imagefield module

hello

D6, imagefields 6.x-3.0-alpha2, CCK 6.x-2.1

i created a content type where users can also add images, but the INPUT field is too large and i want to make it smaller

the original field is:

it is possible to change the size with a little javascript at the bottom of the page.tpl.php file

<script type="text/javascript">
  $(function() {
    $('input.form-file').attr('size', 42);
  });
</script>

that works for the first load, but if you add a picture the INPUT file jumps back to the old size of 60.
if anyone has a way to solve this problem that would be great - this is the last problem i have to solve to finish a project :)

greets
markus