I'm just wondering if theres any way I can add a second onClick event to this piece of code so that it will submit the following form action?

Here is the button code:
<button type="button" title="<?php echo $this->__('Add to Cart') ?>" class="button btn-cart" onclick="setLocationAjax('<?php echo $this->getAddToCartUrl($_product) ?>','<?php echo $_product->getId()?>')"><span><span><?php echo $this->__('Add to Cart') ?></span></span></button>

And i'd like it to submit this form action:
<form action="<?php echo $this->getAddToCartUrl($_product) ?>" method="post" id="product_addtocart_form_<?php echo $_product->getId(); ?>">
</form>