It actually is a rather easy migration compared to other CAD formats.
I assume the files are in Inventor Vault? If you are looking for a quick and dirty way. Use Inventor Vault's "Pack and Go" command, put the files in a location outside of both vaults, then drag and drop into EPDM --relying on EPDM's ability to rebuild the parent child relationships and reading the iProperties.
If the files are not in any kind of vault, then regular drag and drop often does what you need.
If you need to bring in previous versions, or the files are in another type of PDM system you may need to write some code to make the magic happen. I or any other service provider can certainly help you.
What our issue is, is that the old vault and the new vault functionality conflict. We have not finished the migration so we need both sort of active. And the simple (should be) method to disable the existing vault does not work. But that may be a write access issue.
Argh . . Inventor is a pain. First we though it was the conflict between having both vaults active but we still have issues with workinf with Inventor parts and drawings. I need to speak to someone who actually maintains Inventor parts/ assemblies and drawings inside the EPDM system. Anyone?