Based on https://github.com/cms-nanoAOD/nanoAOD-tools
- Set up recent CMSSW release (tested in 10_6_28_patch1 but 10_6_30 should work as well - there's no strong dependence on the version)
- Clone NanoAOD tools from here https://github.com/cms-nanoAOD/nanoAOD-tools
- Clone this repository in the CMSSW src directory