*SPOILER ALER - Heck, this whole thread is a spoiler *
I think the first time I got to the end, I tried for about five minutes (the time it took me to kill him the first time roughly, playing on hard). Then I switched off my saber to punch his lights out, and that's when it happened. ; )
Since then I've tried and tried, but to no avail. I wish you COULD kill him and get a different ending.