The electron-phonon interaction in Li-doped carbon clathrates hex-LiC(40) and hex-Li(2)C(40) has been investigated from first principles. Although the characteristic phonon frequency and electron-phonon interaction are large, the electronic density of states is relatively low which finally gives an electron-phonon coupling constant lambda=0.46 for Li(2)C(40). Hole-doping is expected to provide higher T(c) than n-doping in hex-C(40).