In this blog, http://www.bswebdev.com/2008/12/javascript-change-input-box-type-to-password/ I have found the following snippets for fixing change input type through javascript in IE6.
<script type="text/javascript"><!--mce:0--></script>
# put the script in the head of your html
<input id="pw" name="password" type="text" value="Password" />
What is <script type="text/javascript"><!--mce:0--></script>
?