Here's a quick tutorial on how to add "Pay with STEEM / SBD" options to your Shopify store!

• Within your store's admin control panel, navigate to Settings > Payments and choose "Create custom payment method" from the dropdown in the "Manual payments" section.

• Enter name:
  Pay with STEEM or Steem Dollars
  
  Enter additional Details:
  Choose this option to pay with STEEM or Steem Dollars. You will use Steem Connect to complete the transaction.
  
  Enter payment instructions:
  Please choose a payment method below.

• Under Sales Channels on the side panel, navigate to Online Store > Preferences. Make sure you have Google Analytics enabled and under "Additional Google Analytics Javascript" enter:

try{document.getElementsByClassName('radio__label__accessory')[3].innerHTML = '';}catch(e){};

• In the admin control panel, navigate to Settings > Checkout and place the following code under "Additional scripts"

<script>  
  var steem = new XMLHttpRequest();
  steem.open("GET", "https://api.coinmarketcap.com/v1/ticker/steem/", false);
  steem.send();
  steem = parseFloat(JSON.parse(steem.response)[0].price_usd);

  window.onload = function () {
    total = parseFloat(document.getElementsByClassName('payment-method-list__item__amount')[0].innerHTML.replace("$",""));
    order = document.getElementsByClassName('os-order-number')[0].innerHTML.replace("Order #", "").replace(/\s/g, '');

    steemTotal = total / steem;
    sbdTotal   = total;

    steemitAccount = "thesteemitshop" //Change this to your Steemit account name where you would like to receive payments.

    steemURL = "https://v2.steemconnect.com/sign/transfer?to=" + steemitAccount + "&memo=" + order + "&amount=" + steemTotal.toFixed(3).toString().split(".")[0] + "%2E" + steemTotal.toFixed(3).toString().split(".")[1] + "%20STEEM";
    sbdURL   = "https://v2.steemconnect.com/sign/transfer?to=" + steemitAccount + "&memo=" + order + "&amount=" + sbdTotal.toFixed(3).toString().split(".")[0] + "%2E" + sbdTotal.toFixed(3).toString().split(".")[1] + "%20SBD";

    instructions  = "<button class='btn btn-success' style='display: block;width: 100%;' onclick=\"window.open('" + steemURL + "','_blank')\">Pay " + steemTotal.toFixed(3) + " STEEM

";
    instructions += "<button class='btn btn-success' style='display: block;width: 100%;' onclick=\"window.open('" + sbdURL + "','_blank')\">Pay " + sbdTotal.toFixed(3) + " SBD";

    if (document.getElementsByClassName('payment-method-list__item__info')[0].innerHTML === 'Pay with STEEM or Steem Dollars —') {
      Shopify.Checkout.OrderStatus.addContentBox(
       '
Select Payment Method
',
       instructions
    )};

  };
</script>

This script does the following:

1. Fetches the current STEEM price using the coinmarketcap.com API.
2. Extracts the total final price and order number.
3. Calculate how much STEEM or SBD is needed to pay for the order.
4. Generate Steem Connect links for payment, placing the order number in the memo field of the transaction.
5. Inject two buttons which when clicked open their respective Steem Connect transactions which look like this:

Now customers will be able to checkout using STEEM/SBD and it will be easy to track because the order numbers will match up with transaction memo fields!

Thanks for reading, hope it will be a help to some of you out there, and if you have any comments, concerns or suggestions please don't hesitate to mention them below!