Prototype Javascript Conflict

I’m trying to add this following line to my single post page:

<script type="text/javascript" src="https://comments.socialtrade.com/js/comment-system.js.php?siteid=21"></script>

But I don’t get it to work properly. A programmer said the following:

“There is a problem with conflicting JavaScript on his site. His site uses an old version of the Prototype javascript library, which has a problem that has been addressed in newer versions. easier would be for him to update his Prototype library, but I am not sure how to do that in WP or if that will cause more problems.”

Anyone has an idea how to fix this?

Any help will be greatly appreciated.