Assign User to Category

Ok, first of all, I’ve read THIS thread, and none of the plugins mentioned there seem to work the way I’d like them to. Is there a plugin out there that will do this for me:

Contributor level user may only post to an assigned category AND that category’s sub-categories.

Contributor level user sees only their assigned category/sub-categories in the category selection area of the Add/Edit Post screen.

Thanks in advance for any input!