Well, I think the earliest thing we know is that she was introduced on the Anna Nicole show as being a neighbor. She was on a couple of episodes. I may be too suspicious, but I don't buy that. I think she has some connection to the Stern family.
I'll wager he found her for the show. A script doc.
The only thing I can think is that Anna actually met KE's husband Wes Irwin before the show/neighbor thing. Wes Irwin is a production supervisor.
Wes Irwin's Production Manager BIO (all the movies he has worked on)
http://imdb.com/name/nm0410469/