Welcome @theTvideos to Salesforce StackExchange,
Email to Case Premium uses the standard Case Comment object, it is not part of it.
E2CP is a managed packaged and not a Salesforce object, therefore you can't create records of it.
In regards to your question in the comments section, the Case Comment object is not configurable so you can't add the 'Notes & Attachments' section to it. You can't even add a custom field to it.
However, you can create a custom object which will have the same functionality.
It should have a master-detail relationship with the Case object, and you will also need a Visualforce page to display the records on a case record.
In general, you should write a trigger on the EmailMessage object that will create a record of the new custom object whenever an email is being sent/received. I almost forgot mentioning that you can of course add the 'Notes & Attachments' section to any custom object.