After series of attempts I can answer my own question.
On Ubuntu, clone pg and webwork2 from git, install
sudo apt-get install libstring-shellquote-perl libxmlrpc-lite-perl libjson-perl libdbi-perl libuuid-tiny-perl liblocale-maketext-lexicon-perl
Then copy the perl script sendXMLRPC.pl fom the webwork2 tree to the working directory. Put the ww_credentials file in the working directory and set html_display_command and friends in this file.
Run the command as follows.
perl sendXMLRPC.pl -bv --seed=120 problem.pg
For the first time you have to solve about three the complaints of the script, (missing env variable and two config files) and then everything works nice. Thank you.
Robert