  In this paper, we show how to calculate analytically the one-loop helicity
amplitudes for the process $q\bar{q} rightarrow t\bar{t}$ induced by KK gluon,
using the spinor-helicity formalism. A minimal set of Feynman rules which are
uniquely fixed by gauge invariance and the color representation of the KK gluon
are derived and used in the calculation. Our results can be applied to a
variety of models containing a massive color octet vector boson.
