Systems Management

I have a simple app that I am trying to deploy. The package tries to install through the policy, but an external config file is needed to complete the installation so it fails. I have 2 questions.
1. Where do GPO initiated packages get copied to to execute the installation. Is it windows temp, system32\appmgt or elsewhere?
2. If I need to copy the config file over would I do that with a transform file somehow?

I am unfamiliar with custom transforms so insight would be appreciated or point me to a resource

thanks