From my point of vue, I would say no because HP-UX has no software to do so, mirror-ux will do mirroring, RAID5 is achieved by specialized devices such as HP RAID160 SA Controller:
HP RAID160 SA Controller Supported RAID Configurations
You have an usupported OS (or will be very soon...), but an interesting box, do you have a tape device on it? If so I would do a make_recovery tape (man make_recovery...) and use it to reinstall the OS on one disk (vg00) then mirror it and install the rest on 1 disk (vg01) and mirror also.
Since you have 2 independant controllers I would mirror each time a disk from alternate controller.
You could also try to stripe on 2 disks (each on different controller) then mirror with the 2 other disks left...