If you want to integrate Google+ Comments in your ProcessWire website, just follow the instructions from an article on Browsing the Net. In summary, insert the following HTML code into your template:
<script src="https://apis.google.com/js/plusone.js"></script>
<g:comments href="<?=$page->httpUrl?>" width="642" first_party_property="BLOGGER" view_type="FILTERED_POSTMOD"></g:comments>
Change the width accordingly and in case you have a Google+ profile, link your page with Google+ profile to enable moderation features.