From the Microsoft Dynamics GP Blogs: How to use a GP 2010 Web Service; Deploying SSRS Reports; GP 12 Fave Features: Debugging GP Word Templates
How To Use the Dynamics GP 2010 Web Service: In this blog post, Mike Calvert says "the Dynamics GP web service has a few tricks to it that you have to work through in order to make a call."
Calvert explains that because the web service isn't a straight call, using things like SSIS won't work. And because the system is policy-based you might have to spend some time looking around for rules.
The rules are in the Administrative Tools as Dynamics Security Console, Calvert says. Calvert also tells you what to do if you encounter any errors. He also explains the steps you need to take to maintain policies in Dynamics Security Console.