Stacking projectors

[Ajin]

Need advice on stacking projectors- 2 RS 500's to increase light output especially for 3D.  Have a 160" centerstage XD screen(AT with approx gain 1) with projector 19.5' to screen.  What's the most effective & economical method to align them-pc/os software vs external hardware to assist.  Ken whitcomb did a Sony stack(w5000's) for Art Sonneborn so even that stack makes sense even though the Sony is so bright so my JVC stack should be appreciably brighter.  Appreciate the comments.
Ajin

[AVSMike]

The Sony is easier, because Sony has software to help with alignment. You can do this pretty good, just using the controls on the projector, but helps if you can physically adjust the projectors right, left and up down. Get one projector adjusted to fit a correct rectangle on the screen. Then do the same with the second projector. Then use lens shift to get them as close as you can. This is the point where being able to physically shift the projector right, left and up, down comes in handy. It can be hard to hit exact, just using lens shift. Here is about the cheapest one that I know of.
http://www.chiefmfg.com/Series/LCD

[Tedd]

I am looking forward to seeing Alan Gouger's dual Sim HDR stack, and the Lumagen work and see if this can translate
downward$.....

[Danonano56]

Ajin, did you ever make progress on stacking to RS500s?  I had the same idea, but wonder if it would be too much trouble over the long run.