Magento - How to insert a custom tab in One Page Checkout?

Christian Young quoted
"I found a nice extension from Inchoo which will insert a customizable tab in Magento OnePage Checkout. So I used this extension and extended it a little bit to fit the requirements."

"What I want to do is to add a Terms & Conditions tab before placing an order. So here's the code.
/home/donnafiera/magento/app/design/frontend/default/default/template/checkout/onepage/heared4us.phtml"

<form id="co-heared4us-form" action="">
    <?php
        echo "I have read the <a href='".Mage::getBaseUrl(Mage_Core_Model_Store::URL_TYPE_MEDIA)."test.pdf' target='_Blank'>TERMS AND CONDITIONS</a>";
    ?><br/><br/>

        <label><input id="chkaccept" type="checkbox" name="useraccept" value="yes" />&nbsp;Accept</label><br/>
</form>
<script type="text/javascript">

   function formValidation(oEvent) {
    oEvent = oEvent || window.event;
    var txtField = oEvent.target || oEvent.srcElement;

    var t1ck=true;

    if(!document.getElementById("chkaccept").checked ){ t1ck=false;}

    if(t1ck){document.getElementById("btnTerms").disabled = false; }
    else{document.getElementById("btnTerms").disabled = true; }
    }

    window.onload = function () {
        var btnTerms = document.getElementById("btnTerms");
        var chkaccept=document.getElementById("chkaccept");
        var t1ck=false;
        document.getElementById("btnTerms").disabled = true;
        chkaccept.onclick = formValidation;
    }
</script>
<div class="button-set">
    <p class="required"><?php echo $this->__('* Required Fields') ?></p>
    <div id="heared4us-buttons-container">
        <button id="btnTerms" type="button" class="form-button right" onclick=" heared4us.save();"><span><?php echo $this->__('Continue') ?></span></button>
        <span id="heared4us-please-wait" style="display:none;" class="opc-please-wait">
            <img src="<?php echo $this->getSkinUrl('images/opc-ajax-loader.gif') ?>" class="v-middle" alt="" /> &nbsp; <?php echo $this->__('Loading next step...') ?> &nbsp;
        </span>
    </div>
</div>

Original Article was posted by Mike Christian Young @ http://workingmagento.blogspot.com/2011/02/magento-how-to-insert-custom-tab-in-one.html

Cheers,
Spawn