How do I allow a person to post on my wall without seeing posts from other friends?

[PM89]

How do I allow a person to post on my wall without seeing the wall posts from other friends.

I know you can do this because for some people on my facebook list, I am able to write on their wall, but I don't see anyone else writing on their wall. I know that people do, but I can't see it.

I want them to still be able to write on my wall, but I don't want them to see other posts.
I did this before with one person, but facebook has changed a little, so I'm not sure how to do it again.

Also, is there a way to hide that I'm going to an event on facebook? I only want certain lists of friends to see that I'm going to an event, not all the people I have on facebook.

Thank you!
update: Well, the thing is, in the summer, I was able to make it so that my boss that added me on facebook could post on my wall but she couldn't see my other wall posts. This is also how I see her wall.. I can post, but I can't see if her other facebook friends have posted.
I know it was like this because when I clicked "view as" my boss, that's how I would see my wall from her perspective - that she can post, but she can't see the other posts.

But I feel that things have changed since that time, so I'm not sure how to set this with other people on my fb