You should note that HP-UX 11iv3 enables the default PSET setting for HT by default, but you may still need to enable the firmware setting.
You should also note that HP-UX 11iv2 does not support HT.
All the checks below should return 1 (for enabled).
Check HT is supported in your chipset:
$ getconf _SC_HT_CAPABLE
Check the firmware setting is enabled:
$ getconf _SC_HT_ENABLED
Check the default PSET has HT enabled:
$ kctune -v -q lcpu_attr
Enjoy some HT goodness.