Currently GAT only creates a VS-based setup project. You can definitely create your own WiX-based setup project for your custom guidance package.
The MetaFactory (a superset of GAT)found in the SFT (
http://softwarefactoriestoolkit.net) can create both VS-based Setup projects and WiX-based ones. You may want to take a look at the generated code to check how a WiX-based setup for a guidance package looks like.
HTH,
-vga.
Working with GAX/GAT/DSL? Download SFT now! http://softwarefactoriestoolkit.net