The GALPROP package (http://galprop.stanford.edu) computes cosmic-ray propagation and gamma-ray and other emissions. The extension to synchrotron radiation including polarized emission, 3D magnetic field models, and free-free emission and absorption, is described in a recent paper http://arxiv.org/abs/1309.2947, published version: http://mnras.oxfordjournals.org/content/436/3/2127 .
To support the paper with detailed information, here is a full version with polarization, free-free...