Inject the Contact Picker via console

picker-inject.js

(function(key, opts, s) {
  s = document.createElement('script');
  s.type = 'text/javascript';
  s.async = 1;
  // assign the src attribute
  s.src = "https://api.cloudsponge.com/widget/"+key+".js";
  // set the script to invoke a callback after it loads
  s.onload = function() {
    window.cloudsponge && cloudsponge.init(opts);
  }

  // add the script to the page
  document.body.appendChild(s);
})("YOUR CLOUDSPONGE KEY", {
  // cloudsponge options go here
});

Steps:

1. Right-click on the "To" field and select 'inspect'. The inspector will open and highlight the HTML with the field.
2. Right-click on the highlighted field in the inspector and click 'Edit as HTML'.
3. Add a link to launch the Contact picker: <a href="#" class="cloudsponge-launch">Pick Contacts</a> and update the To field with the attribute class="cloudsponge-contacts".
4. Change to the 'console' tab in the inpsector.
5. Paste this code, edit YOUR CLOUDSPONGE KEY and add any options you want to include. Press enter.