The more recent releases of DBD::Oracle offer a README.hpux file.

More to the point, I got Perl 5.004xx/Oracle 716/HPUX 10.20 working by doing the static link thing described in one of the READMEs. DBD::Oracle 1.06, DBI 1.1x.

All that is lacking now is some pithy saying about old sw to sum up the situation.