You can definately export and import - the format is a text file (Novell Address Book NAB). It's a bit obscure, but if you export first it should be a straightforward search and replace.

The actual address book database is part of the Groupwise PO message store (part of the ofuser files), and you don't want to try attacking directly.

Open the appropriate address book, select File/Export. Export to a NAB, and edit away.

Edit: This is true in GW 5.5 EP (which is supposed to be mostly the same from the DB end).

-jk