CustomPress Custom Post and Capabilities - How to edit role capabilities


I am trying to get the capabilities to this website solidified, and I am having trouble with one piece.

I am attaching screenshots, so you can see what I am talking about.

I created a custom post type "books". I made the capability type "book". I have a role "writers". I don't want writers to be able to have access to any other post type ... I am using "user role editor" to manage my roles and capabilities.

I have everything set, except I want writers to have access to comments, and although I have "comments" checked under my custom post type in CustomPress, comments have disappeared.

Take a look at my CustomPress settings and User Role Editor settings, and let me know what you think.

Comments were visible when I had the "edit post" check boxes checked in User Role Editor, but I don't want the post check boxes checked because I want to restrict access to main posts, and only allow access to books and comments on book posts.