News group/user permissions per category

[eurekafag]

I read this thread and asked for help but no one answered for a month so I have an urge to create a new one. I need to have permissions for every category in the News module so that the user (or a group) can post their news only in one or several assigned categories. I don't see the way to do it using existing settings without hacking the code.

Seems like some people implemented this before but all those attachments are inaccessible now and this code was never included to the upstream. Please, help me!