Here is a video I shot today using the RTH failsafe feature on a DX6i which only has a 2 position switch. The mixing info is in the video information. I hope this helps some guys cause there are a lot wanting to know how to do this.
http://www.youtube.com/watch?v=SHKedPufe08
http://www.youtube.com/watch?v=SHKedPufe08