Couldn't get my paws on a suitable HP-UX 11.23 so I tried on a 11.11 PA-RISC box.
Had to rebuild Openssl (and tweak the Makefile :-( ) and eventually got the dependencies installed.
I attempted to connect but it timed out. This is more than possible due to the corporate firewall ....
/zenus.pl --username xxxxxx\@xx.com --password=xxxxxxxx --account=zenxxxxxx\@zen
500 Connect failed: connect: Connection timed out; Connection timed out at /opt/perl/lib/site_perl/5.8.3/zenus.pm line 130