Hello! Please remember that my responses are informational only, we are not establishing a therapeutic relationship.
One idea that has worked for a few people I know (myself included) was to put a small air mattress at the foot of the bed ---and tell the child that they can come in a sleep on the air mattress, but not in the bed.
I think all 3 ideas are valid, workable ideas --some of this depends on the personality of the child and the parents. I've known people who have used EarthSister's approach with great success, and rddaycare's approach works for some people --but I've also known some parents who do not respond to well to the "keep returning him to his room" approach (myself included). But, her point about not giving attention is a great one ---except one my kids perceived the "taking back to the room" behavior as attention. Also, I was annoyed by having to wake up multiple times. Hence, the air mattress on the floor --no fuss, no big deal, and not in my bed!
So, overall, I think you need to consider that a number of approaches will work --but which one fits you and your child the best?