<li id="captcha-input-box-contacts">
    <label for="captcha_contacts" class="required"><em>*</em>Please type the letters below</label>
    <div class="input-box captcha">
        <input name="captcha[contacts]" type="text" class="input-text required-entry validation-failed" id="captcha_contacts">
    </div>
</li>
<li>
    <div class="captcha-image" id="captcha-image-box-contacts">
        <img id="captcha-reload" class="captcha-reload" src="url/skin/frontend/base/default/images/reload.png" alt="Reload captcha" onclick="$('contacts').captcha.refresh(this)">
        <img id="contacts" class="captcha-img" height="50" src="url/media/captcha/base/4e10928a37926a4c5363ef538901076d.png">
            </div>
    <script type="text/javascript">//<![CDATA[
        $('contacts').captcha = new Captcha('url/index.php/captcha/refresh/', 'contacts');
    //]]></script>
</li>