Activate lab licenses using silent install

[Bart]

We have a MSDNAA subscription, which comes with Lab licenses.
We would like to install Microsoft Office Visio Professional 2007 using the
lab licenses in our computer labs.
We use GPO software installation to push the installation on all computers

I editted the config.xml file with the necessary details such as company
name and product key.
The silent installation using gpo completes without any problems but when
Visio is launched for the first time, the user is presented with an
Activiation dialog box (Activation by phone or internet)

Is there a way to do the activation during the silent install too?

Bart: With volume licenses, we don't experience this problem because those
don't have to be activated, but lab licenses do.