If you currently have Google Tag Manager installed on your site and would like to add the ICS JavaScript to be loaded through a Tagtag, the process is fairly simple to do. Once you have configured the JavaScript installation script as described here, visit your Google Tag Manager account and follow these steps:
Go to Tags and select create a New Tag
In Tag Configuration, select the Custom HTML option
Paste the configured ICS installation script into the HTML Section (Make sure to place the JavaScript inside
<script></script>HTML tags)On the Triggering section, select which pages you want the ICS widget to launch on
Name, save and publish your new tag
Verify and test integration on your site once your new Tag tag is published