The full exploitation of the physics potential of an International Linear Collider (ILC) requires the development of a polarized positron beam. New concepts of polarized positron sources are based on the development of circularly polarized photon sources. The polarized photons create electron-positron pairs in a thin target and transfer their polarization state to the outgoing leptons. To achieve a high level of positron polarization the understanding of the production mechanisms in the target is crucial. Therefore a general framework for the simulation of polarized processes with GEANT4 is under development. In this contribution the current status of the project and its application to a study of the positron production process for the ILC is presented.