Hi colsen,
CuteLiveSupport can achieve it simply.
1. You need to integrating CuteLiveSupport with one site of your website group.
2. Than refer http://cutesoft.net/live-support/Developer-Guide/scr/Adding-chat-button-tag.htm, it shows you how to add the live chat button on your web page.
3. Also, you can simply add this live chat button to other site. Just need to change the src to point to the location which integrate with CuteLiveSupport.
below is the code of us
<script src="http://CuteSoft.net/CuteSoft_Client/CuteChat/Support-Image-Button.js.aspx"></script>
Regards,
Ken