My guess is there is no way to get the custom properties to export. From what I see in general, like all CAD companies, they want you to use there program. They make it easy to import, but difficult to export.
I would look at this more from the standpoint of what can you do at the import stage in Solid Works rather than what you can do with the exports in Solid Edge.
FIgure out what formats and switches are available in SW then work backwards to what is the right export.
As a former works user, I think the best suggestion would be to get a parts list out of Edge that includes all the metadata you want to move, and then write a macro on the works side to re-apply that metadata. Or maybe use the Solid Edge import tool in works (which really just gets the parasolid) and write a macro around that to pull and apply the custom properties for each part. If you ask around on the works forums, you may find that someone already has a macro that will do this.
All of my translations have gone the other way (works to Edge).
Best of luck.
Retired Community Manager for Solid Edge. This account is no longer active.