Open up includes/modules/order_total/ot_insurance.php
Go to line approx. line 214 and change it to this:
Code:
'field' => zen_draw_hidden_field('opt_insurance', '1'))));
That will make your change! Voila!
Though you'll need a couple of tweaks. You'll notice now that the fieldset box that is supposed to surround your insurance text doesn't enclose the text. So open up includes/templates/YOUR_TEMPLATE_NAME/tpl_checkout_payment_default.php and change around line 101:
Code:
<?php echo $selection[$i]['fields'][$j]['field']; ?>
<br class="clearBoth" />
</fieldset>
(you're just adding the <br class="clearBoth" />)
Then of course you want to open up includes/languages/english/order_total/YOUR_TEMPLATE_NAME/ot_insurance.php and change the text to say something like "Shipping Insurance will be added to your order".