Add comments from the admin panel?

I’m using WordPress as an Authoring tool. Hence I do not use the front end.

Now I wanna add the functionality making internal comments. As it is now, you are only allowed to read comments from the Edit Post page, not to write them.

Got any hints or good ideas on how to make this possible?

This will be possible in the upcoming version WordPress 3.4. Try the Beta or just wait.

Here is a screen shot (incomplete translation to German):