Xenforo Plugin - Approve Users To View Post

Write a xenforo plugin. This plugin should give an option when writing or editing a post to add other users on the forum to have access to your post. For example, I might post a thread in a section where only moderators can see it but I also want to give access to this post to a list of other people that are not moderators. I should be able to add or remove users from access whenever I want by just editing the post.