Hi Sean,
The ISRF supplied with GALPROP is provided in energy density units because that is what is used for IC gamma ray production using the angular averaged Compton scattering cross section. That means that it is integrated over 4pi sr and does not retain any angular information about the distribution of the photons on the sky. However, we do actually calculate all of the angular information using a separate code called FRANKIE, and use this when doing anisotropic IC calculations, it is just not currently provided because the total data files are quite large (> several GB for a full ISRF `model'). If you want to use the ISRF angular information as a background the FRANKIE code sky map output could be used, but we should discuss this in more detail since it is quite involved. You can email me:
tporter@stanford.edu.
Troy