Mike,
Here's a link to Boxa.net that shows the process in more detail:
How to - Upgrade to a 996 Instrument Cluster - How To - www.BoXa.net
You will probably need to register on Boxa.net (a UK site) to read it. It's been over two years since I did this work, so my memory is a little fuzzy. I do remember that when you read the code off the chip, you had to swap the bits to make them readable. I forget the steps that I followed to do this, but it was not difficult. The best advice I can give is to not make any changes to either circuit board until you are confident that you have it right. Save a copy of the code that you download from both clusters in case you need to go back to the original programming.