First, setup an area on a disk with a lot of free space. Then type these commands:
setenv USESHLIBS yes
setup cdfsoft2 last integration release
newrel last integration release test
addpkg Stntuple dev_last dev
This lets you use programs like cdfSim and root.
Just for the record, this works for release 3.16.0 and dev_214. I can't promise it will work for any other releases.
Next to generate Z->ee (note that's generating only. we aren't simulating the detector), execute these commands (tcl files based on those provided by Peter Onyisi):
So this should leave you with a root file called zee_pythia_HEPG.stntuple which contains only the GENP bank filled in the Standard Ntuple.
Here's a link to Peter's Page which has some additional information.
Here's a link to the Pythia Homepage where you can view the Pythia manual. In there, it tells you how to customize the file zee_generate.tcl to choose the decay and options you want.