Actually I think I have found a better solution. I did not realize that with the payment module of my choosing that there was an additional "Review Order" page before confirmation. I was able to redirect the links leading to this page by editing the following file:

public_html/includes/templates/template_default/templates/tpl_modules_opc_submit_block.php @ line 18

Simply replacing the line 18 with:
Code:
<span id="opc-order-review">	<?php echo '<a href="https://website3.com/index.php?main_page=checkout_confirmation&template_switch_id=template3&'. zen_session_name() . '=' . zen_session_id()   .'"><button type="button">Review Order</button></a>';?> </span>
seems to have done the job. The only hangup is that the "Review Order" button is using the default Zen-Cart button instead of the one designated for my template. Not a big deal, but I am trying to figure out how to adjust this for the sake of aesthetics. I tried a few changes, but these seem to interfere with the redirect. Any advice?