That's what I had tried first, but:
<pre>
/afs/cern.ch/work/g/giamman/fastsim/mixing/CMSSW_7_0_X_2014-01-20-1400/src/FastSimulation/Tracking/plugins/RecoTrackAccumulator.cc: In member function 'void RecoTrackAccumulator::accumulateEvent(const T&, const edm::EventSetup&, edm::Handle<std::vector<reco::Track> >, edm::Handle<std::vector<reco::TrackExtra> >, edm::Handle<edm::OwnVector<TrackingRecHit> >)':
/afs/cern.ch/work/g/giamman/fastsim/mixing/CMSSW_7_0_X_2014-01-20-1400/src/FastSimulation/Tracking/plugins/RecoTrackAccumulator.cc:107:30: error: no match for 'operator[]' (operand types are 'edm::Handle<edm::OwnVector<TrackingRecHit> >' and 'int')
  NewHitList_->push_back( hits[hit_counter] );
                              ^
</pre>