If you're so inclined, it's pretty easy to make your own cable. Here are the pinouts per the Multibridge manual:
AES IN 1: pin 1 high, pin 14 low, pin 10 ground
AES IN 2: pin 2 high, pin 15 low, pin 12 ground
AES IN 3: pin 3 high, pin 16 low, pin 13 ground
AES IN 4: pin 4 high, pin 17 low, pin 22 ground
AES OUT 1: pin 5 high, pin 18 low, pin 23 ground
AES OUT 2: pin 6 high, pin 19 low, pin 24 ground
AES OUT 3: pin 7 high, pin 20 low, pin 25 ground
AES OUT 4: pin 8 high, pin 21 low
They don't indicate a separate ground for AES out 4, but any of the other ground pins should work fine.
At the opposite (XLR) end, high connects to pin 2, low to pin 3, and ground to pin 1.
This is the same pinout that Yamaha, Mackie, Sony, and Apogee use -- and it's distinctly difference from the Tascam DA88 protocol.
You can find the manual online at
http://www.planetdv.net/Pdfs/Multibridge_Win_Manual.pdf -- the pinout is on page 32.
Regards,
Jeff Hartman
Engineering Project Manager
Newport Television, Northeast