I had to create 6 Sync rules each one with 100+ attribute flows. It would take me at least 2 dedicated workdays to do this repetitive task. My research revealed that the only means available to automate this task is to adapt the Migration deployment steps
FIM 2010 Configuration Migration Deployment Steps
Here is how I adapted these steps to accomplish this work in less than 20 minutes.
Introduction to Inbound Synchronization
Introduction to Outbound Synchronization
SyncPolicy.ps1 In this script make the following changes
$pilot_filename = "updatepolicy.xml"
$production_filename = "policy.xml"
Note that I configured my outbound flow to allow null, if you do not want that you can take it out.
Enter the following for Inbound attribute flows
In Excel copy the formula down column C to all the attributes listed.
I did find that even though no errors were reported during the update processes I had to manually match 3-5 attributes. I will post an update but if you run into this you can update this article too.