If you only want to prepare a simulation in PrePoMax, export it and run from the input file using CalculiX solver outside of PrePoMax (after completion you can import the results to PrePoMax or another postprocessor) then the thread linked in your post is for you.
However, if you want to automate PrePoMax usage from the command line, there is a new functionality for that: A new developer/preview PrePoMax version v2.1.7 has been released - #3 by Matej