  The dipole subtraction method for calculating next-to-leading order
corrections in QCD was originally only formulated for massless partons. In this
paper we extend its definition to include massive partons, namely quarks,
squarks and gluinos. We pay particular attention to the quasi-collinear region,
which gives rise to terms that are enhanced by logarithms of the parton masses,
M. By ensuring that our subtraction cross section matches the exact real cross
section in all quasi-collinear regions we achieve uniform convergence both for
hard scales Q ~= M and Q >> M. Moreover, taking the masses to zero, we exactly
reproduce the previously-calculated massless results. We give all the
analytical formulae necessary to construct a numerical program to evaluate the
next-to-leading order QCD corrections to arbitrary observables in an arbitrary
process.
