I have a VBA script that adds a certain contact to a contacts folder. I also have downloaded the outlook CC extension.
What I am wondering is there any way, either using VBA with or without the extension to update a CC list that I have?
It is certainly possible to do an integration with our API that would allow you to update a Contact through a VBA script. In past developers I've worked with using VBA, this is not as easy as it is when using a .NET application or script as it doesn't have as many ways to do HTTP Requests but it is certainly possible. I would recommend checking out our documentation here: http://developer.constantcontact.com.
Our plugin for Outlook is an Outlook COM plugin written in C#. It is compiled code so it won't be very helpful to you. However, we are in the process of updating this plugin and will be doing so with the C# .NET wrapper that we open sourced at http://github.com/constantcontact. Unfortunately, I don't believe that a .NET DLL is usable in a VBA Script so I'm not sure how helpful this will be for you.
While I'm not an expert in plugins for Outlook, my initial instinct is you wouldn't be able.