Finally the papers associated with the CGenFF program for atom typing and assignment of parameters and charges by analogy are available online:
K. Vanommeslaeghe, A. D. MacKerell Jr., J. Chem. Inf. Model., DOI: 10.1021/ci300363c
K. Vanommeslaeghe, E. P. Raman, A. D. MacKerell Jr., J. Chem. Inf. Model., DOI: 10.1021/ci3003649