  We describe the gauge-invariant treatment of the finite-width effects of W
and Z bosons in the fermion-loop scheme and its application to the six-fermion
(LEP2) processes e^- e^+ -> four fermions, with massless external fermions. The
fermion-loop scheme consists in including all fermionic one-loop corrections in
tree-level amplitudes and resumming the self-energies. We give explicit results
for the unrenormalized fermionic one-loop contributions to the gauge-boson
self-energies and the triple gauge-boson vertices, and perform the
renormalization in a gauge-invariant way by introducing complex pole positions
and running couplings. A simple effective Born prescription is presented, which
allows for a relatively straightforward implementation of the fermion-loop
scheme in LEP1 and LEP2 processes. We apply this prescription to typical LEP2
processes, i.e., e^- e^+ -> \mu^- \bar{\nu}_\mu u \bar{d}, e^- e^+ -> s \bar{c}
u \bar{d}, and e^- e^+ -> e^- \bar{\nu}_e u \bar{d}, and give numerical
comparisons with other gauge-invariance-preserving schemes in the energy range
of LEP2, NLC and beyond.
