Here is a link (from the banner at the top of this page).
There is information from Mr. Ross on Help from cults, interventions, etc. Please see if this information is helpful. I have never been involved in EST or Landmark so I am only an outsider looking in at the horror stories told by 'escapees'.
Perhaps someone who has gone through the abuse can give you some direct personal insight.
Goodluck on your quest to save your friend and I am truly sorry for both you and he/she.