How do I integrate a simple unsigned Google Checkout cart with Google Analytics?

Question

How can I get a simple unsigned cart in Google Checkout to integrate with Google Analytics for ecommerce tracking?

The top Google Results for this all point to documentation for implementations that involve signed carts or server-to server API requests.

(asking to self-answer)

Answer 1

The documentation for how to do this is extremely difficult to find, hence my motiviation for posting and self-answering.

Enabling Analytics Support for Unsigned Google Checkout Carts for Google Analytics ECommerce Tracking:

This method applies for any cart that does not use 'signed' carts or server-to-server API calls. Basically, the 'simplest' method of setting up Google Checkout. If signed carts and server-to-server API calls don't mean anything to anyone, it's probably this way.

First, you must make sure that the standard Google Analytics snippet is not included on pages with the Cart.

Second, you must append an attribute value to the cart.js tag already on the site, as aid="UA-XXXXXX-X", where UA-XXXXX-X is the account code for the site.

Here's the example:

<script id="googlecart-script" type="text/javascript"
src="http://checkout.google.com/seller/gsc/v2/cart.js?mid=MERCHANT_ID"
aid="UA-XXXXXX-X"
currency="USD">
</script>

That's all you need to do. It's shockingly easy to do, but almost impossible to find this documentation, hence my posting here. Hopefully, the power of StackOverflow's SEO will make this easier for people to find.