title: Woocommerce replace add to cart button with custom button/link
body: <p>I need to replace the Add to Cart button (only on certain categories) with a custom button for "Text a Dealer." The "Text a Dealer" button will trigger a gravity form in a lightbox which allows the user to submit a text message over the Twilio SMS service. </p>
  
  <p>Here is a <a href="http://screencast.com/t/qysuRaeul" rel="nofollow">screenshot</a> </p>
  
  <p>I think I know how to link the button to a form in a lightbox but I do not know how to replace the button.</p>