To add a button, edit templates/plugmod/main.php

Look for:
Code: 
<input class="button-auto" type="button" value="<?php echo lang(334); ?>" onclick="location.href='audl.php'; return false;" />
<br />

This is the "Auto Transload" button. On top of this button, add the following code:

Code: 
<input class="button-auto" type="button" value="Multi Transload" onclick="location.href='mudl.php'; return false;" />
<br />