Kudos to Dustin Rush, NAC Architecture
We are in the midst of an e2003-e2010 migration, and the customer has a custom contact form in the organization forms library. Regular public folder replication created the requisite public folder structure on the e2010. The custom form sort of worked in that new items in the contact list used the custom form, that data was intact, but viewing existing contact cards in the public folder reverted to the OOBE view.
Various efforts at enforcing the custom form from Outlook proved fruitless.
Dashing Dustin found this tool (DocMessageClass) that allowed us to modify the object attribute for each of the contacts in the public folder. The process took very little time – maybe 3-4 minutes for 10k+ objects.