You could scan convert the output using the image pro to send to the vision mixer and loop thru the DVI to the LED wall processors. The only way of getting pixel accurate stuff is to use DVI. I've just done this on Muse - DVI from Catalyst thru a Folsom Image Pro (using the loop thru) to Barco Encore (which you can program EDID on), sending an SDI signal to Imag. The Encore takes the DVI from Catalyst as a Background layer (i.e. unscaled) and sends that to the LED wall processor. Obviously, you don't need an Encore to do this... Beware if you use the Image Pro to scale you'll lose a frame and a half...

Hugh