Is it possible to deploy the ZFDAgent.msi using MS AD Group Policy software

I have been working with a client who has an MS AD environment and is using
ZFDAgent via Middle Tier to a single ZFD/eDir server.
We've been trying to silently deploy the client using MS GP, but have had no
success... It appears as if the MSI, isn't a real MSI and hence it isn't
possible to create an MST to deploy it with...

We tried using Wise Install Tailor, but it complained that the MSI was not
capable of using 'hidden' parameters...

Any suggestions/tips truly welcome!!