The coupling of the tunneling- and proton dipolar reservoirs of a weakly hindered methyl group is used to dynamically polarize the rare-spin nuclei by combination with suitable radio-frequency irradiation schemes. H-1-->C-13 and H-1-->N-15 double-resonance experiments below 60 K in a pure gamma-picoline matrix and with 1.5 % N-15-acetonitrile as a guest are reported at a field of 5.17 Tesla. (C) 2003 American Institute of Physics.