Fellow Dynamics GP MVP Mariano Gomez is back with a post explaining how to transfer data between two Dynamics GP companies using the Microsoft SQL Server Import and Export Wizard.
Transferring GP Data with SQL Import and Export Wizard
Sales, Purchasing & InventorySQL & DataDevelopment & Integration
Archived post from 2009. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.