Hi Michael
It should be fairly simple...
I will assume that you have all layers routed to Mix 2 (output2) with mix all layer with Fx selected? and that you are not using any other mixes.
To do this - you will have to use both outputs of the Mac (or use a Matrox DH2G)
Assign all layers in use to both mix 1 and mix 2
Set Mix1 to 1024x768 and align it to 0,0 on Output 1 (Left)
Set Mix2 to 1024x768 and align it to 0,0 on Output 2 (right)
Decide upon your percentage overlap: 20%?
In mix 1 options, change the x offset to -0.8
In mix 1 options, change the x offset to +0.8
This will split the image between both screens with a 20% overlap
In mix options, turn on Blending 'Edge Fade' and 'Blending HUD'
(this will show you the blend and PINK lineup markers
In mix 1 options, enable Blending Right 20%
In mix 1 options, enable Blending Left 20%
Your screens should resemble the picture attached... (but on 2 screens)
Once you physically overlap your projectors by 20% - the pink markers should align and the result will be one widescreen image.
You will have spare pixels on the Left and Right which you probably wont use.
You can increase the overlap - but its usually more difficult to blend a bigger overlap - so start with 20%
I have assumed that you don't need to keystone the image at all here....
Do get back to me if you need help with that too BEFORE spend hours trying to line it up...
Hope this helps
Simon