  We present a first application of a previously published method for the
computation of QCD processes that is accurate at next-to-leading order, and
that can be interfaced consistently to standard shower Monte Carlo programs. We
have considered Z pair production in hadron-hadron collisions, a process whose
complexity is sufficient to test the general applicability of the method. We
have interfaced our result to the HERWIG and PYTHIA shower Monte Carlo
programs. Previous work on next-to-leading order corrections in a shower Monte
Carlo (the MC@NLO program) may involve the generation of events with negative
weights, that are avoided with the present method. We have compared our results
with those obtained with MC@NLO, and found remarkable consistency. Our method
can also be used as a standalone, alternative implementation of QCD
corrections, with the advantage of positivity, improved convergence, and
next-to-leading logarithmic accuracy in the region of small transverse momentum
of the radiated parton.
