the development process ought to be pretty simple:
1. Create a data model for your comments (make sure you provide a way to associate them with content, e.g. ContentID foreign key).
2. Build the Views
for the admin and plug them in existing module
(e.g. Generic Content).
3. Once you get the admin side working, create a new control and inherit from ContentView (more specialized) or ContentBasic (more abstract) class and replace the standard comments implementation there with your own. Alternatively, you can create a new instance of the CommentsList control and in the templates for ContentView (NewsView, BlogPosts, EventsView) replace the CommentsList with your own implementation.
Those are the high level guidelines. Let us know if you get stuck on some implementation steps along the way and we'll try to assist you as much as possible. Also, worth noting is the fact that Sitefinity 4.0 will bring this feature out of the box, so if you are not in a hurry you may decide to wait for a while (we don't have yet the official release date - but it is our next major release).
I hope you'll find this information helpful. Let us know if there is anything else we can do for you.
the Telerik team